Turn off WiFi on T-Mobile Home Gateway

I connected my Apple AirPort Extreme to the T-Mobile gateway with a long ethernet (in the wall) cable, and that works perfectly. I did NOT turn off the WiFi on the gateway. I connected the AirPort to the gateway with an ethernet cable. Then I reset the AirPort. When it came back up it automatically did the setup to extend. Make sure you name the AirPort network the same name and use the same password as the gateway. No loss of speed, and now I have strong connections throughout my long house. When I'm near the gateway, that is the connection. When I'm near the AirPort, then that is the connection.