How do I restore my BT router to its factory default settings?

Hold the reset button on the back panel of your router for about 10 seconds. This can resolve a few common issues with your internet connection.

While your router is on:
Press and hold the RESET button on the back panel of the router for about 10 seconds until all LEDs turn back on, then release the button.
Log in to the web management page of the modem router. Go to Advanced > System Tools > Backup & Restore