Well, these forums seem pretty dead.  Time to move on.

Before I do, just wanted to update the thread with a solution.  I was able to go into phone settings and add a new access point using IPv4/IPv6 APN protocol. The t-mobile default is IPv6, which appears to no longer be working on Plarium's side.  (I was unable to modify the t-mobile access point, so I had to create a new one of my own that I could change the APN protocols).

Hello, I am having the same problem.  I recently got a new phone. A samsung galaxy A11 with Android 10.  Since upgrading, I can only play the game when connected to WiFi.  Attempting to play on cellular network 4G LTE results in the game loading to 75% and staying there until an error message that displays "Timeout" is displayed.  I also have T-Mobile (USA), same as the original poster.  Any ideas on what could be causing the problem?

Sam Loco said:

Hello, I am having the same problem.  I recently got a new phone. A samsung galaxy A11 with Android 10.  Since upgrading, I can only play the game when connected to WiFi.  Attempting to play on cellular network 4G LTE results in the game loading to 75% and staying there until an error message that displays "Timeout" is displayed.  I also have T-Mobile (USA), same as the original poster.  Any ideas on what could be causing the problem?

Hello! Answered you in PM.