Connect to your T-Mobile WiFi network
Open a web browser
Enter your router’s IP address in the address bar
Log in with the router admin username and password
Go to the WiFi, Wireless, or Network settings section
Find the WiFi password, WPA key, or security key field
Enter your new WiFi password
Save or apply the changes
Reconnect all devices using the new password
If needed, restart the router
If you do not know the admin login, check the router label or T-Mobile app
If you cannot access the settings, contact T-Mobile support