P2P Mobile App doesn't work with T-Mobile

[Leroy]

When setting up the P2P connection or Hik-connect, it only works on:

My local LAN (Comcast)
Anyone's WIFI
Verizon cellphones
Sprint cellphones
Haven't tested AT&T cellphones

Both the iVMS-4500 and Guarding Expert client on my Android 7.0 cellphone only works in P2P mode via a non-T-mobile connection.

Has anyone had any problems with T-Mobile using P2P?