Hello. I have a new Flint AX1800 connected behind a T-Mobile 5G home internet gateway. When my computer is connected directly to the T-Mobile gateway I get 100 Mbps download speeds. When my computer is connected to the AX1800, I get 20 Mbps. I know that involves double NAT but that speed loss is terrible.
I want to use a router behind the T-Mobile gateway because there is almost no control in the user interface of the gateway. The only thing a user can do is to change the LAN address range, change the WiFi SSID and password, and turn the WiFi off.
Other users on reddit.com/r/tmobileisp report success using a router behind the gateway, with little speed penalty. Is there anything I can do to improve performance?