You can’t use the Tablo remotely with the T-Mobile router. I really do like T-Mobile home internet, but Comcast is finally in my new neighborhood so I will be switching.
I’m not familiar with that button. Essentially I set it up the same way I did when I had a cable modem and separate wi-if router. You log into the address for the device on a web browser and then enter the values within the Port Forwarding setup option. Again, this is Verizon 5G (not T-Mobile)