Database Users

Constantly receiving WiFi traffic - unstoppable

This is driving me insane!
When I have WiFi enabled at the office, my Samsung Galaxy Note (stock ICS, rooted) constantly receives incoming data and I haven't got a clue which setting, app or service is causing this.
SystemPanel registers a nonstop stream of incoming traffic at 8 to 10 Kbps.
TrafficStats shows an accumulation of Received data under Total WiFi, but can't seem to link it a particular app or service: after resetting the data, no processes appear but the incoming data keeps on growing.
All sync options are off, I've tried to kill every running app or service (one by one, all at once), I've tried to block all traffic using Droidwall. As soon as WiFi is enabled, the incoming stream is unstoppable. When switching to 3G, there's no incoming traffic.
But to make matters even more mysterious, I do not have this problem with my WiFi connection at home.
It only occurs at the office, only on WiFi and (as far as I know) only on my phone.
Any ideas?

This is simply because your wifi antenna still "hears" the data going trough the wireless network on wich you are connecter. Event if your phone doesn't asks for any data at the moment the traffic there is on the network will still be counted by the wifi chip on your phone.
It will be the same on any public network or if you have another phone or a computer connecter on the same wireless router and generating traffic.

Thanks for replying, John!
That sounds very plausible, but then I still have to figure out why only my phone is registering this traffic - maybe it's an ICS thing or brand specific?
And I'll try to 'reproduce' it at home by connecting a laptop at the same time.

I think that the above is correct. That may be default behavior.
Sent from my XT862 using xda app-developers app

Well, I've tried to connect several devices at once on my home WiFi network, but it did not reproduce the incoming traffic problem I experience at work.
There were a few incoming bytes registered, not nearly as much as the constant stream of 10 Kbps at the office network...

Your works wifi may be set up like that. Who Knows?
Sent from my XT862 using xda app-developers app

MrObvious said:
Your works wifi may be set up like that. Who Knows?
Click to expand...
Click to collapse
Well, our it-department certainly does not.
You're probably right that this is normal behavior. I'll just have to figure out which drains less battery under these circumstances, WiFi or 3G. Thanks anyway for replying.

I'm on the mobile app, but if you have GSM then just switch to 2g until you use it.
Sent from my xt862 using xda app-developers app

Djezpur said:
Well, I've tried to connect several devices at once on my home WiFi network, but it did not reproduce the incoming traffic problem I experience at work.
There were a few incoming bytes registered, not nearly as much as the constant stream of 10 Kbps at the office network...
Click to expand...
Click to collapse
About this, it is simply that at your office there is traffic on the network (download/upload) while at home simply having devices connected doesn't generate traffic or almost none. Start several dl on several devices (phone laptop) (guess 2-3 is enough, maybe even one but not sure, not en expert after all ) then you should notice signifficant traffic on your phone, I guess!

So interesting I find this thread because I have the exact same problem!!!!
How I noticed it...when I am at home I drop 1% battery on Wifi per hour. 10hours = 10% (sometimes less).
I go to work on the Wifi, I DONT USE ANYTHING ON THE PHONE and the battery is DRAINING LIKE CRAZY!!! 5%/h or more!!!
( I am in airplane mode in both place)
So I was thinking, WTF with this work wifi, i am not doing anything at all on it. Then I look at my wifi icon I have a constant RECEIVE icon. And I bet my phone does not go to sleep or something.
So why in the world my work wifi is draining my battery and the one at home is not. I will check tonight but I dont think I have traffic like this. I am registering 5-6kbytes/s for nothing. The explanation given above is hands-waving. I do not agree with it fully. YEs sure there are several pings and beacon emitted back and forth but i do not think it is enough to cause 5-6kbytes/sec . The wifi is not in Monitor mode and it only receives the packets destined to my phone.
This is madness!!!! BTW When I had a different kernel on back on ICS this behavior stopped. I will try to monitor again.

kalinusa said:
So interesting I find this thread because I have the exact same problem!!!!
(...)
This is madness!!!! BTW When I had a different kernel on back on ICS this behavior stopped. I will try to monitor again.
Click to expand...
Click to collapse
Hey kalinusa, did you find a solution to this problem?
I'm currently on the SpeedMod kernel, but that does not seem to make a difference to the 'office WiFi behavior' (so I keep my phone on mobile data).

I don't want to speak out of my ass, because I haven't a clue how the app works.
As far as I can guess SSH tunnel may help you. I would hope someone else could tell me I'm right, but I'm probably wrong.

I have had this same problem with two of my devices. The first is a Samsung Captivate with the last AOKP ICS build. The second is a Google Nexus 7 with AOKP's first Jelly Bean build (it happened when I had stock as well).
This only happens when I'm connected to WiFi at my university. The down arrow on the WiFi icon is ALWAYS on and it drains the battery. At home, I don't have these problems.
I emailed my university's IT department but I'm not sure if there's anything they can do. Anyone have any suggestions? Thanks.

I have exactly the same problem, but I think I found the reason which is causing it. I think that some of the routers are capable of the multicast over the wifi and then we can get a constant wifi traffic. I tested it at home, where I have enabled multicast over wifi and my phone wifi receiving the data all the time, even if it is in sleep. Now I'm in the office where we do not have such capable router with multicast over wifi and my phone wifi behavior is as expected. When I will be at home I will test it again with my router and with disabled multicast over wifi and hopefully it will solve this issue.

danielo said:
I have exactly the same problem, but I think I found the reason which is causing it. I think that some of the routers are capable of the multicast over the wifi and then we can get a constant wifi traffic. I tested it at home, where I have enabled multicast over wifi and my phone wifi receiving the data all the time, even if it is in sleep. Now I'm in the office where we do not have such capable router with multicast over wifi and my phone wifi behavior is as expected. When I will be at home I will test it again with my router and with disabled multicast over wifi and hopefully it will solve this issue.
Click to expand...
Click to collapse
More than multicasts it could be broadcasts, what are you reaceiving. For example if you don't use WINS server in Windows domain, all computers use broadcast to get IP address for a computer name (if you dont use DNS name, but that's another story). At home, where aren't many computers, there are very few broadcasts. But somewhere, where a large amount of computers is on the same network (not splitted to broadcast domais), number of broadcasts would dramatically increase

btw. if you connect a PC to the same network as your phone and stop ALL running applications (mainly instant messangers, web browsers, e-mail clients) you should see the same network bandwidth in use as on your cell phone.

More than multicasts it could be broadcasts, what are you reaceiving. For example if you don't use WINS server in Windows domain, all computers use broadcast to get IP address for a computer name (if you dont use DNS name, but that's another story). At home, where aren't many computers, there are very few broadcasts. But somewhere, where a large amount of computers is on the same network (not splitted to broadcast domais), number of broadcasts would dramatically increase
Click to expand...
Click to collapse
Interesting. Roughly how many devices would need to be on the same network, to see that kind of traffic load?
-- Sent from my TouchPad using Communities

post-mortem said:
Interesting. Roughly how many devices would need to be on the same network, to see that kind of traffic load?
-- Sent from my TouchPad using Communities
Click to expand...
Click to collapse
It depends on what you consier as network load. If you start a network monitor like Wireshark or MS Network monitor and even if there is one computer on the network, you wil see "some" traffic (from time to time a few network packets). To generate constant network load, you'll need a few dozens of computers. And it always depends on how the network is designed and what applications the computers run. If all computers connect to a server, the network load will be a lot lower than if the computers share resources among them.
Or you can design your network in such way, that you divide computers into segments, where computers can communicate only with computers in its segment (or with some distant servers). This way the network load will dramatically decrease, as computers from different segments would not interfere.

I currently only have one computer connected to my home network atm via wifi, and it keeps a constant broadcast going to my phone for some unknown reason. I thought it was my dlna server, so I shut that off, and it is still broadcasting _something_... Its causing quite a battery drain, and unfortunately I cant seem to find the root of the issue. I've trolled through my router settings -- multicasting isnt on -- so Im at a loss. =\

Spz0 said:
I currently only have one computer connected to my home network atm via wifi, and it keeps a constant broadcast going to my phone for some unknown reason. I thought it was my dlna server, so I shut that off, and it is still broadcasting _something_... Its causing quite a battery drain, and unfortunately I cant seem to find the root of the issue. I've trolled through my router settings -- multicasting isnt on -- so Im at a loss. =\
Click to expand...
Click to collapse
It can be caused also with the Media servers which runs on PC, also DHCP etc. It is not easy to eliminate all broadcast traffic and sadly our phones react at all that multicast packets.

VPN works fine in Wi-Fi but not with 3G

I'm hopeless here. I have a paid VPN service, and it works perfectly with my PC, with my mobile on Wi-Fi and with my friend's mobile also on 3G, but not on mine. For sure there's something wrong with my device. I tried hard reset, different ROMS and all different servers and settings.
It does connect to the VPN and it keeps up the connection, but internet just doesn't work. Anyone have any idea why this is happening? I tried to search other threads about this, but no success.
Thanks
Raphael

Same here ... I search but nothing ... I'm on Ressurection Remix 3.1.3 with Kernel cm 10.1... VPN in 3G don't work

Have you tried the app Go to my p.c. app?
Sent from my HTC Sensation XE with Beats Audio Z715e using xda app-developers app

vpn thrue 3g and mobile connection
hi
reason, routing.
1. you have to setup your vpn connection to route any data between your vnp-connection.
or
2. you use another apn who route unsecured and secured data to different routes.
(secured data = VPN, unscured Data => www)
Check the isp apn if it use a stateful paket inspection firewall. this apn can ussually only route secured data (vpn).
Its no bug its a feature to solve some problems like too much connections, timeouts, reduction of hacker attack surface, and more..
you can find this information in the special vpn-whitepaper from your isp.
i hope this helps you.

How does the go to my p.c. app work?Is it pretty good app. Thanks
Sent from my HTC Sensation using xda app-developers app

3g provider at fault
raphaelgoncalves said:
I'm hopeless here. I have a paid VPN service, and it works perfectly with my PC, with my mobile on Wi-Fi and with my friend's mobile also on 3G, but not on mine. For sure there's something wrong with my device. I tried hard reset, different ROMS and all different servers and settings.
It does connect to the VPN and it keeps up the connection, but internet just doesn't work. Anyone have any idea why this is happening? I tried to search other threads about this, but no success.
Thanks
Raphael
Click to expand...
Click to collapse
One thing I notice not all 3G provider allow VPN traffic. Orange is one that I discovered not allow VPN via 3G.

tinbox134 said:
One thing I notice not all 3G provider allow VPN traffic. Orange is one that I discovered not allow VPN via 3G.
Click to expand...
Click to collapse
When you set up the VPN on your phone, make sure you fill out the forwarding fields as 0.0.0.0/0.0.0.0 otherwise no traffic will be forwarded through it. Testing on wifi from the same location as the host is a miserable way to test VPN as it tells you nothing. Turn off the wifi, and always test on your mobile data. There ARE carriers out there that WILL filter out VPN connections for normal user accounts and require you sign up under a business-class account to use such connectivity, this is because they want more money from you, and to not give you an easy way to get around their tethering detection. Plus in some countries, you're not allowed to possess the capability to encrypt and secure your own data/traffic and the means of encryption are banned (and therefore filtered "on-the-wire").

Use VPN Service that has open port. Like http://xtreamvpnworld.blogspot.com ive been using it for more than a year. I got no problem.
Sent from my WT19i using xda premium

@ephraim25.. sir may be you can help me with my problem i've already established my vpn all working except for all my chatting application not working i can't recv any reply like my viber,talk,skype,tango.. but if i turn off my vpn everything run smoothly.
btw.. i'm using samsung galaxy s3 built-in vpn, everything stock but rooted.

rapnix said:
@ephraim25.. sir may be you can help me with my problem i've already established my vpn all working except for all my chatting application not working i can't recv any reply like my viber,talk,skype,tango.. but if i turn off my vpn everything run smoothly.
btw.. i'm using samsung galaxy s3 built-in vpn, everything stock but rooted.
Click to expand...
Click to collapse
That's seems odd. Anyway I haven't tried built in vpn, how about openvpn? Have you tried it? I think built in vpn doesn't support voips like viber etc. Or maybe your vpn provider does not. I really don't know. Because I tried using droid and xtream vpn it works on every chatting platforms.
Sent from my WT19i using xda premium

@ephraim25 tnx sir.. i'm going to try that open vpn tnx again....

No problem just tell me if you had set up so I can give you free premium vpn account access.
Sent from my WT19i using xda premium

@ephraim25 well that's great tnx i'll try this
ok i've installed already OpenVPN for android then how can i have this FREE PREMIUM vpn?

[Q] Facebook app cannot connect via mobile network on Nexus 4

My Facebook app (including Messenger) cannot connect to Facebook over my wireless network. This has been happening for weeks now. All of my other apps, including the browser, can connect to the internet over my wireless network with no problems (I can even access the Facebook mobile website via the web browser). The Facebook app will only work over WiFi. When on my wireless network, it just shows "updating" for a long time, until eventually displaying a "network error" message.
There have been a few times in the past couple weeks, however, where the app will connect and update over the wireless network. Unfortunately, this only lasts a few hours or so, and then it resumes not working again. Perhaps this means I'm having account issues.
I have tried clearing the app data/cache, uninstalling and re-installing the app, restarting my phone, etc. to no avail. I am using stock Android on a Nexus 4.
Anyone else having this problem? I've searched the web for this problem, and information seems to be scarce.

Someone started this same thread already. Its got something to do with the newest update. Use friendcaster for the time being is my only suggestion.
Sent from my Nexus 4 using Tapatalk 2

MunkyButt said:
Someone started this same thread already. Its got something to do with the newest update. Use friendcaster for the time being is my only suggestion.
Sent from my Nexus 4 using Tapatalk 2
Click to expand...
Click to collapse
Happening to me too but friendcaster doesn't work either. I am forced to download a dns changer and set them to opendns and then it mysteriously works fine. Native app and all. Started with the LTE rollout here in San Diego

djdanska said:
Happening to me too but friendcaster doesn't work either. I am forced to download a dns changer and set them to opendns and then it mysteriously works fine. Native app and all. Started with the LTE rollout here in San Diego
Click to expand...
Click to collapse
Yeah, Friendcaster didn't work for me either.

I think I figured it out... The Facebook app has problems when WiFi is on when there is not a WiFi connection. If you turn off WiFi it seems to work on the wireless network.

Actually, that didn't work. Oh well. Back to using the mobile website.

Edit your APN settings to use IPv4 only and not IPv4/IPv6. See if that makes a difference.

Ajfink said:
Edit your APN settings to use IPv4 only and not IPv4/IPv6. See if that makes a difference.
Click to expand...
Click to collapse
Thanks for the suggestion, by my APN is already set to only use IPv4. However, the app has suddenly started working again, which makes me think this whole problem is server side. Hope it lasts. Crossing my fingers.

WiFi Issues

Hello all,
I just recently upgraded from a GS6 Edge + using JoD, and admit I'm loving this phone. However, I'm experiencing a weird issue that (I believe) relates to my home network.
Here is what happens: I successfully connect to my network and all seems well. I have Internet with full bars. I can browse and watch videos with no issues. But when I go to the Play store, I cannot download any apps. They just say “downloading” and never actually initiate the download.
My temporary workaround that I've found to work is to disconnect and reconnect to my network, and I'm able to get 1 or 2 downloads before I experience the issue again.
If anyone has any ideas on a permanent solution, please let me know. Or if you need more information to help.
Thanks in advance!
Sent from my SM-G935T using Tapatalk

I've experienced the same issue you're having on my office Wifi. The strange thing is when I connect to the office guest network, all is well. I'm also not able to download any photos from Google Photos so not sure if it's a google DNS thing or what. No issues on my home Wifi either.

wpbcubsfan said:
I've experienced the same issue you're having on my office Wifi. The strange thing is when I connect to the office guest network, all is well. I'm also not able to download any photos from Google Photos so not sure if it's a google DNS thing or what. No issues on my home Wifi either.
Click to expand...
Click to collapse
Ok, I'm glad to hear I'm not alone (despite issue being bad). I think it might be a Google thing, because I've also found that I can't setup Google accounts on the WiFi because it just hangs on the log in and never actually logs in. I can switch to data and all is well.
I've also been on a different network that worked with no issues, similar to your case with the guest network. Seems to be something with a very specific type of network...
Sent from my SM-G935T using Tapatalk

There's definitely some WiFi issues with the phone. I use WiFi Calling at the office and if I get out of range from the router in my office, it will not reconnect until I turn the screen on and unlock the phone.

Same here wifi is fine except with downloading from play store

I've had some WiFi issues as well. Sometimes, I'll have a full WiFi signal yet I lose all connection on my phone. I know my WiFi still works because I can access it from the computer or a Tablet. The only way to get the WiFi on the GS7 working again is by turning it off and back on.

I've noticed this too, but it seems to kill all internet and i have to cycle it..also I've noticed WiFi off several times
Sent from my SM-G935T using Tapatalk

Ok guys, I'm hoping it's just a software issue with Samsung's Marshmallow that will be fixed soon. It's a shame considering the phone is so great in other aspects.
Sent from my SM-G935T using Tapatalk

I think I fixed the issue by using google dns, but I actually did more than that. I reconfigured my home network to use on asus router instead of the old motorola from att which cannot set dns and handle heavy traffic
Sent from my SM-G935T using Tapatalk

cruel91 said:
I think I fixed the issue by using google dns, but I actually did more than that. I reconfigured my home network to use on asus router instead of the old motorola from att which cannot set dns and handle heavy traffic
Sent from my SM-G935T using Tapatalk
Click to expand...
Click to collapse
I'm glad that worked for you. On my end, setting the DNS to standard Google 8.8.8.8 and 8.8.8.4 don't fix the issue. I don't think my router is to blame as it's a fairly new Linksys and all the settings seem to be set up properly as I've never had the issue before this phone. I might need to tinker more though.
Sent from my SM-G935T using Tapatalk

TheShoxter said:
I'm glad that worked for you. On my end, setting the DNS to standard Google 8.8.8.8 and 8.8.8.4 don't fix the issue. I don't think my router is to blame as it's a fairly new Linksys and all the settings seem to be set up properly as I've never had the issue before this phone. I might need to tinker more though.
Sent from my SM-G935T using Tapatalk
Click to expand...
Click to collapse
I've got an older Linksys N dual band at the office, upgraded to run DDWRT, and a Netgear AC router at home. I can reproduce the issue both places, so I'm confident it's an issue with software that T-Mobile/Samsung need to address.

NotATreoFan said:
I've got an older Linksys N dual band at the office, upgraded to run DDWRT, and a Netgear AC router at home. I can reproduce the issue both places, so I'm confident it's an issue with software that T-Mobile/Samsung need to address.
Click to expand...
Click to collapse
Ok, well then I guess we should all try contacting T-mobile and letting them know about WiFi issues. I don't want to have this phone ruined by poor net code or whatever it is.
Sent from my SM-G935T using Tapatalk

TheShoxter said:
I'm glad that worked for you. On my end, setting the DNS to standard Google 8.8.8.8 and 8.8.8.4 don't fix the issue. I don't think my router is to blame as it's a fairly new Linksys and all the settings seem to be set up properly as I've never had the issue before this phone. I might need to tinker more though.
Sent from my SM-G935T using Tapatalk
Click to expand...
Click to collapse
Though it was fixed, I still think it's something wrong with the software because I have several android devices (including both 5 and 6 android), but only two S7 edge have this issue.

I finally fixed the issue for me by setting the DNS of my router itself to Googles Public DNS addresses. Previously I thought changing it on the phone in network settings would do that, but apparently not! Now my phone is working great on my network.
Still an issue that needs to be addressed because some networks we don't have access to change anything.
Sent from my SM-G935T using Tapatalk

I've been going back and forth with T-Mobile and Samsung on Twitter regarding my issues. Samsung wanted me to take my phone to Best Buy, where there is a Samsung Experience kiosk, and have it reloaded with factory firmware. I told them I already downloaded it from SamMobile and would just flash it myself in ODIN. Did that last night after backing my stuff up to the computer, and not a single difference has been made.
My WiFi is rock solid, as long as I don't walk out of range from the router. If I do, it will not reconnect until I turn the screen on. No need to unlock it, just need to turn it on.
Also have a ticket in with T-Mobile for the poor radio performance compared to the Note5. We'll see where that goes.

NotATreoFan said:
I've been going back and forth with T-Mobile and Samsung on Twitter regarding my issues. Samsung wanted me to take my phone to Best Buy, where there is a Samsung Experience kiosk, and have it reloaded with factory firmware. I told them I already downloaded it from SamMobile and would just flash it myself in ODIN. Did that last night after backing my stuff up to the computer, and not a single difference has been made.
My WiFi is rock solid, as long as I don't walk out of range from the router. If I do, it will not reconnect until I turn the screen on. No need to unlock it, just need to turn it on.
Also have a ticket in with T-Mobile for the poor radio performance compared to the Note5. We'll see where that goes.
Click to expand...
Click to collapse
Does it still connect to mobile data when the wifi turns off?

jrwingate6 said:
Does it still connect to mobile data when the wifi turns off?
Click to expand...
Click to collapse
Yes it does. However my office is not in a Band 12 area and the signal is fluctuates between Edge and very weak H+. As soon as I get away from my section of the building however, full LTE and no need for WiFi.

I think this is the same problem I was having. Here's a link to my solution.
http://forum.xda-developers.com/tmo...e-via-wifi-t3335579/post65904586#post65904586

cfmarque said:
I think this is the same problem I was having. Here's a link to my solution.
http://forum.xda-developers.com/tmo...e-via-wifi-t3335579/post65904586#post65904586
Click to expand...
Click to collapse
Although that may very well make it work, this is still something that Samsung and/or Google need to address as not every router's settings are accessible to everyone especially at work or public hotspots.

wpbcubsfan said:
Although that may very well make it work, this is still something that Samsung and/or Google need to address as not every router's settings are accessible to everyone especially at work or public hotspots.
Click to expand...
Click to collapse
I know this won't help many (or anyone 'cuz lock bootloader ), but I think I might've disabled IPv6 on my previous phones, but you need root for that.

Switch back to cellular when wifi has no internet, but keep wifi connected

tl;dr: When my phone (Sony Xperia Z5 compact, Android 6) connects to a wifi with no internet, I want to use the local network on the wifi but use the internet from my mobile data. Instead what happens mobile data doesn't switch back on while connected to wifi with no internet.
I have been trying to find a solution for this since forever. My camera creates a local wifi connection which I can connect to to view the camera as well as controlling it. The downside is that while connected to this network my cellular data gets switched off, despite this wifi network not having any internet. So while using my camera I have no way to access the internet. It wasn't a huge problem up until recently when the app I use is introducing livestreaming. I really want to use it but I am unable to find any way how to keep my phone connected to this wifi network (and being able to use it), while any internet data goes over 4G. I am using android 6.0.1. I am quite sure I was able to do this on my previous phone with an older Android version but I cannot find said option (smart network switch or something?) anymore in the wifi settings. Nor any recent similar topics with people with the same question? Anyone that knows more about this?
My phone is rooted. If I need to do any system changes I can do that.

I didnt get what you were trying saying.Do you know that you cant use mobile data and wifi simultaneously unless your device is rooted.If your phone is rooted then try using "download booster"

hh950430 said:
I didnt get what you were trying saying.Do you know that you cant use mobile data and wifi simultaneously unless your device is rooted.
Click to expand...
Click to collapse
Err, sorry, lol. I have wifi network that has no internet, just a local network. I'd like to be connected to that wifi network AND be able to use internet over my mobile data both at the same time. As it is right now, my mobile data gets disabled even when the wifi network has no internet access.
I have talked to two friends of mine about it and both say this is already possible in Android. One friend sent me a screenshot of an option he has in his wifi settings called 'Switch to mobile data' which gets enabled when the wifi network has no internet. My other friend said he doesn't have this option but claims it has been a default feature of Android since lollipop. He tested it on his phone and indeed it works as expected. Both have an unrooted phone with stock Android. So now there is me with my brand new phone and Android 6 and I can't find this option nor does it seem to do what I want by default. I'm confused.
As I mentioned, my phone is rooted so if there is a way to turn this feature on using root, I can totally do that if someone knows how.

As i said try using "Download Booster" It allows you to use wifi and mobile data at the same time just google it.

hh950430 said:
As i said try using "Download Booster" It allows you to use wifi and mobile data at the same time just google it.
Click to expand...
Click to collapse
That appears to be just a download manager if I am correct? I don't need to download anything. I just want to be able to use my existing apps to use my mobile internet when I am connected to wifi (that has no internet).
This is the exactly the thing I'm after. Screenshot from my friend's phone (LG G4 with Android 6.0): (*link removed). My other friend who also has this functionality working has a Nexus 5 with Android 6.0.1.
* Forum doesn't let me post screenshots.. But basically in his wifi settings he has an option called "Switch to mobile data". The box says "Internet unavailable via connected Wi-Fi. Stay connected to Wi-Fi, but use mobile data. Data charges may apply."
Again, I have Sony Xperia Z5 compact with Android 6.0.1 and I can't find this. Have I bought the wrong phone or is it fixable? At this point I am more than happy to even take a custom rom route.

You cannot use wifi and internet at the same time as they are completely different hardware components, using different air waves, so there's no conflicts between them. Better use internet through your wifi or use bluetooth tethering.As for the "switch to mobile data option" it disconnectes you from your wifi if it has no internet and connects you to your mobile data so it doesnt lets you use your wifi and mobile data at the same time

hh950430 said:
You cannot use wifi and internet at the same time as they are completely different hardware components, using different air waves, so there's no conflicts between them. Better use internet through your wifi or use bluetooth tethering.As for the "switch to mobile data option" it disconnectes you from your wifi if it has no internet and connects you to your mobile data so it doesnt lets you use your wifi and mobile data at the same time
Click to expand...
Click to collapse
It actually clearly mentions that it keeps connected to the wifi. He tested it and indeed he could use the local network on the wifi side and use the internet through his mobile data simultaneously. Both friends haven't rooted their phones or anything. This is just a default functionality for them. I have now tested it also on my older phones (Oneplus One and HTC One M8) and all phones can't have both connections open at the same time.
This wifi network is created by my camera by the way and I can't change much about it. The DJI drone I control does the same thing. When I am connected to the camera or drone I lose my mobile internet connection.
I don't have any other device that has access to internet here. We don't have cabled internet, only mobile internet.
Interestingly, in the developers options there is an option called "Mobile data always active" ("Always keep mobile data active, even when Wi-Fi is active"). I've tried it many times, rebooted my phone but this doesn't actually do anything. Even with this option on when wifi is connected the mobile data gets turned off.

This is beyond annoying!
I too have struggled to find a solution to this problem. I do not have a WAN connection to my home network. It is LAN only. I have four PC's, three Sonos speakers, two hdhomerun TV tuners, and various hand held devices that all use the LAN. All I want to do is be able to use my Moto X Pure to control Sonos and file sync to my LAN via wifi and simultaneously use mobile data for WAN stuff. I know the mobile connection is active with wifi enabled because I can see it when running if config, up route show etc... I am trying to learn about the routing tables to see if I can fix this myself. I love my android devices and am loyal, but this is beyond dumb! Any suggestions????

How to fix for android
okay so for anyone who doesnt know still go into the about phone option in your phone settings, then click on kernel version, build model, etc til one pops up with a flash notification saying click so many more times and youll become a dev. once you done that go into the developer menu and scroll too wifi assist or force mobile data upon wifi connection. exit out , open your app , bobs your uncle

Thank you for the answer.
I tried with my Huawei but it doesn't work. Could you tell with which phone you made it work ? Thank you !!

Ok here we go, after 12 years this my first post.
Above suggestions related with developer options nothing to do with OPs requirement. Those option only allows the device rapidly switch to mobile data when the WiFi signal gets weak. Since you always close to your DSLR camera it solves nothing because WiFi signal is always strong.
Root cause of the problem is you can not have 2 default gateways (i.e. router address) for your networks in any operating system (Actually you can but you have to set static routes, which is a pain in the ass for regular users)
iOS handles this in a very simple way. Set your wifi connection to static IP address instead of DHCP and leave your default gateway or router address blank. Viola you can have 3G/LTE data while you connected your camera and now you can sent your downloaded pictures via Whatapp while you still connected to your camera via WiFi. (In my case Panasonic Lumix)
I stumbled upon this thread via Google since I needed the same thing now with Android. But iOS way failed. Actually I am shocked that you cannot leave WiFi Gateway address blank in Androdid 8.0! Save button grays out if you leave it blank. This is really weird. At least with Galaxy S8 Duos with Android 8.0
So anybody know how to setup a WiFi network without a default gateway, please share.

Is this phone specific or something? Never had that happen, I have no problem with wifi being on without internet and using cell data.
I don't think the UI really exposes anything like it directly but you can technically have multiple gateways; it's not something your average user will understand (policy routing)..
Having said that, if you're attached to an AP you should at least see a /24 route out your wireless interface (standard dhcp lease). It's quite common for the AP to have client isolation but are you sure you're not using something like Wifi Direct or even adhoc?

Similar Experience
I have been through this experience long ago. All I did was to sell the phone and bought a new one.