Unable to connect Chamberlain garage door opener via 5g internet

After many hours of trying all options, talking with the (useless) T-Mobile tech support, and reading T-Mobile forums, seems that not only is there an issue , between what Chamberlain needs and what T-Mobile accommodates this is a moving target and depends on router version and MyQ version. Different people have different solutions. I could not get MyQ to work through either of two standalone WiFi routers that were physically connected to the T-Mobile router to connect, that is unless I had the standalone WiFi router network open - no passcode.  Ironically, MyQ works fine through my T-Moblie 5G phone hotspot. So I'm done fooling with this, left the standalone WiFi network open and had the standalone router MAC filter and only accept the MAC addresses of my garage door, phone WiFi, and laptop WiFi & ethernet ports.  Note that MyQ is not the only device that does not connect via the out-of-the-box T-Mobile gateway plus the gateway is the worst router, as far as features available, I've come across since setting up my first WiFi network in 2001.