cellular data doesnt work on ios 14.5 anymore!

Sta2lt wrote:

Pss575, Yes it does make TMobile useless.They will tell you it's your phone, NOT. Mine works just fine on Visible. I am now running Visible and Tmobile side by side on my Iphone12 pro. NO issues with Data on Visible. I will likely move to Visible is it proves to be reliable for the next couple weeks, so far it's great!

I use my Pixel device right next to my GF's iPhone 12 Max Pro. When testing she will get slower speeds. For example one time she was getting 4.5 - 25 Mbps and I will get 300 on 5g. We have tested at numerous locations. Even pulled the sim out to reseat it. Next is to either use eSim or get another SIM card.
It wasn't always that way prior to 14.5/.6 releases. Something is up with Apple's firmware compatibility with the T-mobile network. So yes it is does seem to also be a phone compatibility problem. Numerous people are having this issue with iPhones and some Samsung devices. Hopefully 14.6+ will fix these issues. 

If LTE Only doesn't work for you:

I have the same issue but my phone is iPhone 12 Pro Max. At first I though it have the problem with my carrier then I put my sim on Android is working fine. Then, I realized it not thing wrong with my carrier. The problem I have is the combination between T-mobile sim and iPhone12 Pro max (ios14.6). The iOS 14.6 seems not to working with 5G or LTE. Then, I download the newest version of iOS (14.7 beta).  Now it works (5g unreliably, LTE reliably). I hope my solution will help your guys. 

Always try simple things first (Im sure apple support and Tmobile will make you do them and send you through the loops)

I download the new version on the Apple Beta Software Program.

Same thing here I'm on TMobile Essentials NCC and on iOS 14.5.1 on my 12 Pro. 5G shows full bars but won't load anything on my socials or in Safari. Only when I switch it back to LTE only in settings will it work

¡Problema resuelto!  I too had a "No Credit Check" account, running iOS 14.6 on an iPhone 12 Pro and for some reason had the same issue where the phone indicated it had access to 5G, but internet was not working.  Interestingly, using the SpeedTest.net app, I was able to see fast internet connection (I assume that it's using ICMP to test the connection speed) but all other internet traffic such as HTTP or video/audio streaming was still not flowing. Working with a T-Mobile rep we switched my device to use the digital sim as suggested by Izual, but it still did not work.  Eventually I got cellular data flowing again after switching from a "No Credit Check" account to a T-Mobile Essential account.  I had my credit frozen due to the Equifax breach from a few years ago, so I temporarily unfroze it, they ran a credit check on me, and switched my account to a T-Mobile Essential plan, which actually saved me $10 per month. As soon as the switch took effect, cellular data started flowing as normal again.

This is circumvented by activating your iphones "digital sim" (aka: "esim" or "dual sim") in place of the physical iccid you are currently assigned. You can complete this by contacting customer service and/or tech support, provide them your "EID" (Settings->About->eid) notice youre device should be showing your current imei + iccid network information, along with a second inactive "imei". The second imei you see is not actually relevant or needed for your esim device  activation/switch - the "EID" is what is necessary. after providing this information to the rep, they should direct you to add a new cellular data plan by either sending you a configuration profile, a QR CODE, or manual settings (T-MOBILE.GDSB.NET)

once you activate your esim, you can take your physical sim out and leave the sim tray empty or begin utilizing “dual sim”

your iphone will now receive its intended data connection and available 5G coverage.

*may take an hour or so to register the change, you will need to restart device as well as potentially activate airplane mode for a few minutes and restart.

Pss575, Good luck. They posted 2 20 dollar credits to my account but never solved the issue. My daughter on the same account has the same issue with her 10s. I had 3 tickets elevated but they all came back with it's your phone. My sim card ran fine in the phone at the Tmobile store, but feature this they were running 14.1 IOS. Everyone is very sorry and friendly but I was only able to get 2 of 4 people who promised to call me back to do so. I posted on the Facebook page and got the best help there from Heidi but with the same end result. My post was not totally positive about Tmobile and they pulled my post down. If you get a resolution or not please post back here so we can she what happened. GRACIAS

STA2lt - I called customer service. They told me that they are upgrading the next work settings on the two phone lines ( coincidentally the IPhone 12 phones on that line) and that was the issue. They said a tech would reach out. This is a major issue on their side given they immediately credited my account $15 without asking. I'm giving this 2 days and then I'm leaving T-Mobile. How can you not address such a big issues with the flagship IPhone 12 and leave 100s of customer with essentially a brick phone ( no cell data ). 

Pss575, Yes it does make TMobile useless.They will tell you it's your phone, NOT. Mine works just fine on Visible. I am now running Visible and Tmobile side by side on my Iphone12 pro. NO issues with Data on Visible. I will likely move to Visible is it proves to be reliable for the next couple weeks, so far it's great!

This happened to us with the 14.6 update from Apple. All IPhone 12s on our No credit check family plan have zero cell data although we have full bars. This makes T mobile absolutely useless - needs to be fixed ASAP

T Mobile has decided that it's my phone and nothing wrong with the plan. My sim runs just fine on the phone at their store that is running 14.1. Apple has been completely through the phone and it has no hardware issues. TMobile says the phone is under warenty and get anew phone from Apple, Apple says no issue with phone so no warranty. I am sure it's a problem with the plan and 14.5 OS, T Mobile has not reason to step up being it's an out dated plan. I am going to search another provider.