H2O SIM in ATT Phoenix 4 (LM-X210APM) would not register on network
I've an unlocked ATT Phoenix 4 (LM-X210APM) that is on the approved and supported list. I'm unable to register on the network with my carrier's SIM H2O (ATT MVNO). No cellular voice/data, however, Wifi Calling does work.
I've had success with a Moto G Stylus, but that is not phone for this SIM.
Any suggestion on what I can try to resolve this?