Database Users

Note 3 Rubbish Signal... wrong modem? help needed

Hi, I bought my note 3 in UAE and I am using it in the UK. I am on Vodafone. I always get rubbish signal in my house. It is on "emergency calls only" nearly all the time. Also the LTE/4G has NEVER worked since I got it on launch (Sep). Whenever I turn the 4G on the H+ sign never comes up. Some people may argue that Vodafone is a rubbish network. I agree too but I think I may need to flash a different modem? My model is a SM-9005. Do I need to flash a different modem to get the 4G to work? Thanks

hayat55 said:
Hi, I bought my note 3 in UAE and I am using it in the UK. I am on Vodafone. I always get rubbish signal in my house. It is on "emergency calls only" nearly all the time. Also the LTE/4G has NEVER worked since I got it on launch (Sep). Whenever I turn the 4G on the H+ sign never comes up. Some people may argue that Vodafone is a rubbish network. I agree too but I think I may need to flash a different modem? My model is a SM-9005. Do I need to flash a different modem to get the 4G to work? Thanks
Click to expand...
Click to collapse
You can actually try a different ROM or maybe a custom ROM? At the same time, reception might just be poor in your house. So you might need to make do with regular 3G or EDGE. I no for a fact that in my friend's house i ALWAYS have to switch to 2G because 3G reception is never available, I have SM-N900 tho.

stanley08 said:
You can actually try a different ROM or maybe a custom ROM? At the same time, reception might just be poor in your house. So you might need to make do with regular 3G or EDGE. I no for a fact that in my friend's house i ALWAYS have to switch to 2G because 3G reception is never available, I have SM-N900 tho.
Click to expand...
Click to collapse
I know but when I do have good reception the 4G never works even outside as well
Sent from my SM-N9005 using Tapatalk

hayat55 said:
I know but when I do have good reception the 4G never works even outside as well
Sent from my SM-N9005 using Tapatalk
Click to expand...
Click to collapse
And how about when you set it to HSPA only?

UAE's LTE bands won't work with Vodafone.
Sent from my CM11 Kitkat powered N9005

radicalisto said:
UAE's LTE bands won't work with Vodafone.
Sent from my CM11 Kitkat powered N9005
Click to expand...
Click to collapse
what if i flash a different rom/modem?
I just checked and vodafone operates 4G/LTE at 800MHz. On the samsung uae website it says that the note 3 supports 800MHz 4G/LTE

ROM's won't make a difference as it's the hardware on the device itself.

I also noticed the note 3 doesnt have a superb signal reception... For example in my house my moms s3 and dads s4 have full bars where i on my note have one bar less than they do. Little dissapointed

metko said:
I also noticed the note 3 doesnt have a superb signal reception... For example in my house my moms s3 and dads s4 have full bars where i on my note have one bar less than they do. Little dissapointed
Click to expand...
Click to collapse
Check phone status in settings and compare it with the S3 and S4 - you'll see it's just the bar's that show different the dBm's are what counts. You'll see it'll be identical to the S3/4

radicalisto said:
Check phone status in settings and compare it with the S3 and S4 - you'll see it's just the bar's that show different the dBm's are what counts. You'll see it'll be identical to the S3/4
Click to expand...
Click to collapse
Good point didnt thought of that

I have the same uae version in Kuwait and also had 1 signal bar at home. Flashed Polish KK after root and now I get 3 bats at all times.

Tarzan- said:
I have the same uae version in Kuwait and also had 1 signal bar at home. Flashed Polish KK after root and now I get 3 bats at all times.
Click to expand...
Click to collapse
Didn't that trip knox?

Bump... can anyone help me on which modem i need to flash? I checked and the UAE note 3 supports my UK carrier LTE band. Apart from this I always get crap signal.

hayat55 said:
Didn't that trip knox?
Click to expand...
Click to collapse
Flashing official firmware won't trip knox
hayat55 said:
Bump... can anyone help me on which modem i need to flash? I checked and the UAE note 3 supports my UK carrier LTE band. Apart from this I always get crap signal.
Click to expand...
Click to collapse
The device itself has the bands. But you cannot access them by changing the modem. The N9005 supports many many bands but different MPN Codes on each device limit it to specific countries.
It's all a legal thing. Radio frequencies are controlled, unless the UAE version supports the exact same frequency that your UK carrier runs on it won't work. Upgrade to kitkat and test it.
Sent from my CM11 Kitkat powered N9005

Tarzan- said:
I have the same uae version in Kuwait and also had 1 signal bar at home. Flashed Polish KK after root and now I get 3 bats at all times.
Click to expand...
Click to collapse
I did say after root. So yes Knox tripped but I don't care.

help me please share that modem
N9005XXUGBOD3

How is the Reception on T-Mobile for people who bought the unlocked SM-G935F version

Any issues with the Unlocked version in using it to T-Mobile?

[EDITED for accuracy] Yes - weaker signal on T-Mobile than the S5, with the unlocked international SM-G935FD (dual SIM). This might be due to the metal body around the antenna, or weaker modem.

Dandv, you are an idiot. Quit giving people false information. Your phone does get lte. You have an international version. Just because your phone says 4g doesn't mean your not getting lte. Everyone but the US labels lte as 4g. What the label says in the top right corner of your phone has no bearing on what you are getting as far as the international version goes. Here's how it breaks down international to us version. LTE=4G on international version. H+=What T-mobile calls 4G. H=3G and so on. It's just labeling and has nothing to do with what you are actually getting. If you don't believe me you can switch the network in the settings from lte to 4g and it will change the symbol from 4g to h+. Now, your signal is a whole different issue. A-the modem that came with your phone might not be optimized for T-mobile but you can find a different modem to try and flash via Odin. B-the phone supports all bands from every region. And C-the modem in the s7 might be weaker than the s5. My modem in my s6 is weaker and it's because of the metal body. This is very well known and could be found out if you did some research. Everything that I am telling you can be Googled if you don't believe me. This is suppose to be a helpful forum for people with questions so please stop giving false information.

miller1821 said:
Dandv, you are an idiot. Quit giving people false information. Your phone does get lte. You have an international version. Just because your phone says 4g doesn't mean your not getting lte. Everyone but the US labels lte as 4g. What the label says in the top right corner of your phone has no bearing on what you are getting as far as the international version goes. Here's how it breaks down international to us version. LTE=4G on international version. H+=What T-mobile calls 4G. H=3G and so on. It's just labeling and has nothing to do with what you are actually getting. If you don't believe me you can switch the network in the settings from lte to 4g and it will change the symbol from 4g to h+. Now, your signal is a whole different issue. A-the modem that came with your phone might not be optimized for T-mobile but you can find a different modem to try and flash via Odin. B-the phone supports all bands from every region. And C-the modem in the s7 might be weaker than the s5. My modem in my s6 is weaker and it's because of the metal body. This is very well known and could be found out if you did some research. Everything that I am telling you can be Googled if you don't believe me. This is suppose to be a helpful forum for people with questions so please stop giving false information.
Click to expand...
Click to collapse
I know it's not what was asked. but ZERO issues on ATT network with 935F.

In some regions they dont name it LTE, its Just 4G or 4G+. so if it displays 4G then you are on LTE

Any comments on International vs. T-Mobile version as far as everyday use and performance on T-Mobile? I'm trying to decide which version I should get. I like the absence of bloatware, etc. on International version (though T-mobile probably has the least of the big 4 carriers), and possibly better/more frequent (?) updates.

GeodudeFFP said:
Any comments on International vs. T-Mobile version as far as everyday use and performance on T-Mobile? I'm trying to decide which version I should get. I like the absence of bloatware, etc. on International version (though T-mobile probably has the least of the big 4 carriers), and possibly better/more frequent (?) updates.
Click to expand...
Click to collapse
The international version doesn't completely lack bloatware. My G935FD has a bunch of apps that you can't remove (unless you root the phone): S Planner (a calendar, which keeps begging for permission to display notifications, via another notification!), MS suite (Word, Excel, PowerPoint, OneNote, OneDrive, Skype), Samsung's browser (Chrome is already installed), an Email client, Facebook app that you can't remove if you want to use Metal instead, Samsung Gear (even if you don't have any Gear devices, you can't uninstall it) etc. There are lots of threads on debloating the S7.

I got the Dual sim version using it in hawaii and everything seems fine for me, no changes from my tmobile note 5.

dandv said:
The international version doesn't completely lack bloatware. My G935FD has a bunch of apps that you can't remove (unless you root the phone): S Planner (a calendar, which keeps begging for permission to display notifications, via another notification!), MS suite (Word, Excel, PowerPoint, OneNote, OneDrive, Skype), Samsung's browser (Chrome is already installed), an Email client, Facebook app that you can't remove if you want to use Metal instead, Samsung Gear (even if you don't have any Gear devices, you can't uninstall it) etc. There are lots of threads on debloating the S7.
Click to expand...
Click to collapse
That's not really bloatware at least like it is in the US, but I know what you mean.
Sent Via My Samsung S7 Edge

dandv said:
The international version doesn't completely lack bloatware. My G935FD has a bunch of apps that you can't remove (unless you root the phone): S Planner (a calendar, which keeps begging for permission to display notifications, via another notification!), MS suite (Word, Excel, PowerPoint, OneNote, OneDrive, Skype), Samsung's browser (Chrome is already installed), an Email client, Facebook app that you can't remove if you want to use Metal instead, Samsung Gear (even if you don't have any Gear devices, you can't uninstall it) etc. There are lots of threads on debloating the S7.
Click to expand...
Click to collapse
Agreed, that's a lot of junk I don't need, but at least it's without the carrier bloatware.
How about real-world performance...any differences I would notice (i.e., the pros/cons)?

GeodudeFFP said:
Agreed, that's a lot of junk I don't need, but at least it's without the carrier bloatware.
How about real-world performance...any differences I would notice (i.e., the pros/cons)?
Click to expand...
Click to collapse
exynos are better than SD820 in term of dev and battery live

DUOS on T-Mobile
I just received my DUOS today. Ijbterms of reception, seems about half as weak a signal as from my s6 edge I upgraded from.
My major concern is the 4G vs LTE connectivity. I understand how most of the world dubs LTE as 4G, however my worry is not what tiny icon displays in the corner of the screen, its the performance...
My s6-edge was getting the "LTE" speeds of 15mb/s down but now I'm currently faced with speeds 70% slower.
I've checked in settings under Sim manager and mobile networks, but can't seem to change anything.
I know there was mention of finding the right modem firmware to flash onto the phone depending on region of use, can anyone advise me what I might try switching it to?

DJ.A-BOMG said:
I just received my DUOS today. Ijbterms of reception, seems about half as weak a signal as from my s6 edge I upgraded from.
My major concern is the 4G vs LTE connectivity. I understand how most of the world dubs LTE as 4G, however my worry is not what tiny icon displays in the corner of the screen, its the performance...
My s6-edge was getting the "LTE" speeds of 15mb/s down but now I'm currently faced with speeds 70% slower.
I've checked in settings under Sim manager and mobile networks, but can't seem to change anything.
I know there was mention of finding the right modem firmware to flash onto the phone depending on region of use, can anyone advise me what I might try switching it to?
Click to expand...
Click to collapse
What do you have when you dial *#0011# ?

Hi, any luck getting band 12 to work?

Also if you guys can recommend a good app/way to mesure reception strentgh I have both a 935F and 935T running on T-mobile so I can measure speeds if needed - in my apartment (in NYC) I seem to be getting less signal on the international than on the Tmo (1-2 bars vs 4), but call quality is fine.

Remix22 said:
Hi, any luck getting band 12 to work?
Click to expand...
Click to collapse
The phone has band 12 but it won't connect to it with tmobile. It needs tmobile specific files which the international rom doesn't have which is bs.
Sent from my SM-G935F using Tapatalk
---------- Post added at 12:14 PM ---------- Previous post was at 12:11 PM ----------
Remix22 said:
Also if you guys can recommend a good app/way to mesure reception strentgh I have both a 935F and 935T running on T-mobile so I can measure speeds if needed - in my apartment (in NYC) I seem to be getting less signal on the international than on the Tmo (1-2 bars vs 4), but call quality is fine.
Click to expand...
Click to collapse
There are plenty of signal in the play store. But don't be tricked by bars. Tmobile plays around with bars and dB values. The international version keeps it real. It'll tell you the truest bar value in my opinion. With tmobile, where most phoned would show 2 bars, tmobile will show 3-5 bars on their phone, making you think you have excellent service everywhere
Sent from my SM-G935F using Tapatalk

dandv said:
Facebook app that you can't remove if you want to use Metal instead, Samsung Gear (even if you don't have any Gear devices, you can't uninstall it) etc. There are lots of threads on debloating the S7.
Click to expand...
Click to collapse
Well, I managed to get Facebook off my phone and I'm not rooted
Sent from my SM-G930F using XDA-Developers mobile app

SD here on tmo, no issues. Better reception than on my iphone 6 plus on tmo.

ssgunner20 said:
SD here on tmo, no issues. Better reception than on my iphone 6 plus on tmo.
Click to expand...
Click to collapse
hi, I just got the 935f and still have a 935t, I compared signal reception and strength between the two, see my post in the t-mobile section, oh and I get LTE over band 12. One funny thing is that the 935F seems to connect to different towers than the t-mobile one I have no idea why... http://forum.xda-developers.com/showpost.php?p=66740184&postcount=47

So I have the 935f and here's some things I'm seeing. It does have band 12, though no Volte. When I do *#0011# it shows the phone as being in band 12. Now here's the thing, in band 12 on T-Mobile the speed is nowhere near the speed of Band 4, but the phone seems to want to stay in Band 12. I've used a "connection stabilizer" app and it does seem to "bump" the phone into Band 4. I'm no expert on this stuff, but this is my personal experience as the phone is "stuck" in band 12 otherwise. I'm just north of Detroit, and here are my speedtest results in my house. Keep in mind I have never had good reception in my home, 2-3 bars max.
On 2 bars at time of test in my house
Band 12 down 1.71 Mbps up .12 Mbps
Band 4 with app on down 18.90 Mbps up .19 Mbps
Does someone know a better fix for this than an app, it works but it's a major battery drain .

No LTE on At&t with G935F

I just bought the 935F and I am stuck on Edge data. I also have the At&t model of the gs7 edge and I get full LTE and good speeds in the exact same spot. Same sim card, and I believe I'm using the correct APN settings. I want to switch to the international model because at&t ruins this phone with bloatware. I get a lot of lag on the at&t gs7 edge, and no lag at all on the 935F. Now I just need the LTE to work!!
Anyone able to try and help? I did search the forum first and didnt see anything relevant.

do you see 4G instead but not LTE on your 935F? US carriers call HSPA+ 4G (while it's 3G+) so when their branded phones are in LTE they add an LTE (or 4G LTE for tmobile) icon. My G935F always shows 4G but it's actually LTE. You can dial *#0011# to check for reception or download the LTE discovery app to check your reception

Remix22 said:
do you see 4G instead but not LTE on your 935F? US carriers call HSPA+ 4G (while it's 3G+) so when their branded phones are in LTE they add an LTE (or 4G LTE for tmobile) icon. My G935F always shows 4G but it's actually LTE. You can dial *#0011# to check for reception or download the LTE discovery app to check your reception
Click to expand...
Click to collapse
Thank you very much for the reply. I see E for edge data. I think I may have made some progress by changing the APN settings though. I am seeing LTE now, but the speeds are terrible. Nothing close to what I was getting with the ATT branded version of the GS7E.
Anyone know exactly what APN settings the G935F should be using on ATT? I have unlimited data, so I want to be able to use it!

toptekjon said:
I just bought the 935F and I am stuck on Edge data. I also have the At&t model of the gs7 edge and I get full LTE and good speeds in the exact same spot. Same sim card, and I believe I'm using the correct APN settings. I want to switch to the international model because at&t ruins this phone with bloatware. I get a lot of lag on the at&t gs7 edge, and no lag at all on the 935F. Now I just need the LTE to work!!
Anyone able to try and help? I did search the forum first and didnt see anything relevant.
Click to expand...
Click to collapse
It has nothing to do with the APN, but you have to tell AT&T you have an AT&T branded phone and give them an imei of that phone. Or your 935F will not be able to get lte.

Psyscope said:
It has nothing to do with the APN, but you have to tell AT&T you have an AT&T branded phone and give them an imei of that phone. Or your 935F will not be able to get lte.
Click to expand...
Click to collapse
Hmm, Ok thank you. I'll try that now. I haven't been on att in years, and don't remember having to do that but I will now.

Yeah if you don't have an ATT branded phone they will limit you to the 4g network and not the new LTE network. I bought a cheap Motorola LTe phone that was an at&t approved. I gave them its imei, and I started to get lte.

Psyscope said:
It has nothing to do with the APN, but you have to tell AT&T you have an AT&T branded phone and give them an imei of that phone. Or your 935F will not be able to get lte.
Click to expand...
Click to collapse
Ok so I worked with At&t and gave them the IMEI, but still no LTE data

Psyscope said:
It has nothing to do with the APN, but you have to tell AT&T you have an AT&T branded phone and give them an imei of that phone. Or your 935F will not be able to get lte.
Click to expand...
Click to collapse
No, you do not have to give AT&T the IMEI of your 935F phone.
I just got back to the US, popped my AT&T SIM card in my new intl S7e (935FD) and LTE works as it should. I get speeds of >10 Mbs
LTE bands 2 & 17 are used (in my area - Portland)

Not getting full speed LTE
I have the 935FD S7E. I just went to the AT&T store as I needed a nano sim. The guy who helped me did a Speed Test right next to me performing the exact same test. His AT&T S7 was receiving in the mid to high 30's for download speed while I was getting in the mid 20's. He checked the APN, we assumed that I was getting an LTE speed even though no LTE icon showed. However his S7 was receiving significantly consistent faster data rates than I was getting.
Is there anything I can do to resolve this?

This will be the main hindrance for me buying the international version. If someone gets the LTE thing figured out I'm all in
Sent from my SAMSUNG-SGH-I337 using XDA-Developers mobile app

For what it's worth, AT&T LTE problems in my case were caused by custom ROM.
I just got International S7 Edge (G935F), and without thinking, rooted it and installed SuperMan-ROM 1.8.1. In that state I did have LTE formally, but speeds were very bad. Tried turning data on/off, changing APNs - nothing helped. As a result, in some places data connection barely worked (1.0 Mbps down / 0.1 Mbps up), and the best result reported by SpeedTest was around 4 Mbps up/down. At the same time, when I moved this SIM card into older XPeria phone, it consistently showed ~15 Mbps up/down, which was normal performance for me on AT&T prepaid in NYC. Unfortunately, I didn't check LTE performance with the original default ROM on the Edge, but I recorded all versions.
I went back to stock ROM using this German stock firmware. It was possible to switch to English during installation. Other downloads in that thread are dead links. I immediately did official OTA update, and after that, I now have normal LTE performance on AT&T (15+ Mbps).
I am pretty sure that at least in my case, the radio which the custom ROM insisted I have (G935FXXU1APEQ) was the problem. After going back to stock, I have baseband G935FXXU1APD1, which is what I had out-of-the-box.

cozzamara said:
For what it's worth, AT&T LTE problems in my case were caused by custom ROM.
I just got International S7 Edge (G935F), and without thinking, rooted it and installed SuperMan-ROM 1.8.1. In that state I did have LTE formally, but speeds were very bad. Tried turning data on/off, changing APNs - nothing helped. As a result, in some places data connection barely worked (1.0 Mbps down / 0.1 Mbps up), and the best result reported by SpeedTest was around 4 Mbps up/down. At the same time, when I moved this SIM card into older XPeria phone, it consistently showed ~15 Mbps up/down, which was normal performance for me on AT&T prepaid in NYC. Unfortunately, I didn't check LTE performance with the original default ROM on the Edge, but I recorded all versions.
I went back to stock ROM using this German stock firmware. It was possible to switch to English during installation. Other downloads in that thread are dead links. I immediately did official OTA update, and after that, I now have normal LTE performance on AT&T (15+ Mbps).
I am pretty sure that at least in my case, the radio which the custom ROM insisted I have (G935FXXU1APEQ) was the problem. After going back to stock, I have baseband G935FXXU1APD1, which is what I had out-of-the-box.
Click to expand...
Click to collapse
Imgo to try this you flash via Odin?

Bad or inconsistent LTE speeds with International S7 Edge Duos on AT&T

Has anyone experienced bad or inconsistent LTE speeds on the International S7 Edge Duos while on AT&T? I was out walking the dog yesterday and my speeds were ranging anywhere from 0.3 megabits/second to 12 megabits/second depending on which block I am on. This morning, on my commute to work, I had anywhere from 2 megabits/second speeds or 32 megabits/second speeds depending on where I am on the road.
Is the International not nearly as good with using AT&T band LTE? Is there perhaps an APN setting I should be making? Or should I just learn to live with this?
Thanks in advance

No one has encountered this at all? Perhaps it's emblematic of a potential defect?

Im on att using g935fd, no issue with lte. Im ranging from 15-30 mbps depending on the area. im in boston,ma

in dallas with a 935FD and i've been getting average 29mb down/19mb up... check your APN and also consider testing with another sim card if you have one available.

I'm having the same issue. There is definitely something going on with the Duos. I'm on T-mobile and experience weaker signal (10-15 dBm) on Duos than I get on my 935T sitting next to it. I've flashed several modems, csc's and firmwares. Nothing has helped. Even lost signal last week at a clinic and had to tether of my wife's T-Mobile s7 edge.

VinylJStar said:
I'm having the same issue. There is definitely something going on with the Duos. I'm on T-mobile and experience weaker signal (10-15 dBm) on Duos than I get on my 935T sitting next to it. I've flashed several modems, csc's and firmwares. Nothing has helped. Even lost signal last week at a clinic and had to tether of my wife's T-Mobile s7 edge.
Click to expand...
Click to collapse
It got so bad that I am returning the phone. The speeds I was getting was just too low to make it a useful device.

Maybe its the rom. What firmware you guys are using? I flashed the stock g935f PHN firmware, CSC, AP and then OntheedgeLite UX rom.

There was another posst with OP having similar issue. I have issue as well. But flashing BTU csc ap bl and cp helped me gain better 4g around my home, so I thought problem was fixed. but when I go to poor reception areas and phone is switching to 2g/3g bands, I lose 4g unless restart or messing with sim options switching 4g between sim1 and sim 2.
currently on stock samsung touchwiz rom. BTU cp, csc, ap, and bl

Is it missing the appropriate at&t bands ? I'm looking at note duos as an alternative to the ATT version a day it's meant to be the same chipset and that misses one of the LTE bands.
Sent from my SAMSUNG-SM-N920A using XDA-Developers mobile app

G975F/DS on Tmobile

I just bought this G975F/DS, seems to work just fine, but when I install my Tmobile SIM in the phone it doesn't connect to any networks. Are there settings I need to add/change? Anything?

Netconn said:
I just bought this G975F/DS, seems to work just fine, but when I install my Tmobile SIM in the phone it doesn't connect to any networks. Are there settings I need to add/change? Anything?
Click to expand...
Click to collapse
Check to see which bands are used in your area. If they primarily use band 71 then your SOL because that model doesn't support it.
Sent from my SM-G975U1 using XDA Labs

Netconn said:
I just bought this G975F/DS, seems to work just fine, but when I install my Tmobile SIM in the phone it doesn't connect to any networks. Are there settings I need to add/change? Anything?
Click to expand...
Click to collapse
Probably the access points need to be configured.
Sent from my SM-G975U using Tapatalk

When I inserted my T-Mobile SIM in the US unlocked S10+ for some reason the T-Mobile APN settings didn't autopopulate and I had to enter them manually.
Definitely look at your APN settings.

Well, it finally connected to Tmo but the reception isn't very good. My S7 and S5 pick up much better. Not that happy with it

Netconn said:
Well, it finally connected to Tmo but the reception isn't very good. My S7 and S5 pick up much better. Not that happy with it
Click to expand...
Click to collapse
Use an app like Cellular-Z to see what band each device is using. If the S7/S5 is using band 71 then you wont be able to get as good of coverage on the S10 because the international version doesn't support it.
Sent from my SM-G975U1 using XDA Labs

Netconn said:
Well, it finally connected to Tmo but the reception isn't very good. My S7 and S5 pick up much better. Not that happy with it
Click to expand...
Click to collapse
Did you actually check the APN settings on your S10+? If they are incorrect that would account for your poor reception.
It depends on where you live obviously but my phone never uses band 71 which I think is primarily for rural areas.
I've owned multiple unlocked phones that didn't support band 71 and have never had weak reception on T-Mobile anywhere I've gone.

I have the dual sim with T-Mobile and I actually didn't have to do anything. It worked out of the box.

Akujin said:
I have the dual sim with T-Mobile and I actually didn't have to do anything. It worked out of the box.
Click to expand...
Click to collapse
I haven't needed to manually enter APN settings on a phone in at least 5 years and I've owned a bunch of phones but for whatever reason the T-Mobile APN settings did not autopopulate on mine.
I have a single sim Snapdragon model--whether the T-Mobile settings autopopulate correctly might differ depending on the S10+ model and specific firmware the phone is running but it didn't seem like the OP actually checked his APN settings. I initially had a poor network connection because the settings on mine were not correct.
My reception was excellent after I manually entered the correct APN values and rebooted.

F models cannot do the proper Carrier Aggregation that TMO (and maybe ATT) uses to give their highest speeds and best signals.
While the Exynos models will work, if you have a USA based phone in the same spot you will find the speeds are much faster on the USA based phone than the Exy versions.
As of now, there is no way around this, people have been trying for years.