Each endpoint has a physical reset button. See the endpoint's data sheet for the location of the reset button. Use the following procedure to perform a factory reset from the endpoint:
Disconnect any devices that are physically connected to the endpoint. Leave only the power cord connected.
With the router powered on, press and hold the reset button for at least 10 seconds.
After approximately 10 seconds, the modem and Wi-Fi LEDs will blink twice, and the reset is complete. Release the reset button.
Allow approximately two minutes for the endpoint to finish rebooting before attempting to access the endpoint's configuration.