The latest on the problem:
we found out that our servers do not run well with some LTE networks that runs on IPv6. Users that switched to IPv4 solved the issue that way. We are currently working on an update that will allow all IPv6 to connect without problems.
Thank you for your update!
I can confirm creating a copy of the T-mobile APN on my phone but switching it to use IPV4 instead of IPV6 fixed the problem for me.