Anyone at T-Mobile know how their Home Internet product works?

Two main issues I have right know are the inability to port forward and the inability to change the IP address on the 5G Nokia tower gateway (or the trash can, as it’s been called).

Re: Response to the two "issues".

Home internet routers/gateways will have what is referred to as NAT which is where port forwarding would come into play. The new 5G gateways also have NAT the rules on the NAT solution are strict and port forwarding is not an option. Support cannot help you with that in any way.

The default IP addressing on the 4G LTE gateway you have, I suspect that is a 4G LTE gateway is of course 192.168.1.1/24 on the 192.168.1.0/24 Class C private network. So, with the newer 5G gateways T-Mobile does NOT allow the change to the private network 192.168.12.0/24 to anything else and the gateway IP address would be 192.168.12.1. The DHCP server that runs on the gateway provides the scope for dynamic addressing and also cannot be changed.

If you are satisfied with the 4G LTE gateway and can continue using that then why change? From the information I have seen the 4G LTE gateway allows the web GUI interface for management. The newer 5G gateways, the Arcadyan and the Sagemcon both require the use of the T-Mobile home internet mobile application on your cell phone for management access. If you have an Apple iPhone my experience tells me you would probably be very disappointed with the experience. The FAQs on the T-Mobile pages provide information about the various gateways. I guess you have the Askey LTE GW.

https://www.t-mobile.com/support/home-internet/askey-lte-gateway.html