UBR LTE Newbie: How to choose priority of WAN connections

Hello, I’m wondering how to set the priority of WAN connections in the UBR LTE. I’m installing it in our RV so my wife can work online. In the UBR LTE there are two SIMs, AT&T and Verizon, and I will be connecting a T-Mobile 5G “Home” Internet box via Ethernet. Obviously the signal availability and strength of each carrier will vary widely when traveling.

Any advice will be greatly appreciated.

Yeah, I should have gone for the full 5G router, but it’s too rich for my blood.