How to reset Apple WiFi router

Reset button.

See https://support.apple.com/en-us/HT201945

Edit .. beaten by Bob by that much.. holds up thumb and forefinger with 1nm spacing.

BTW we use google search.. much easier than asking questions here.

There are 3 kinds of resets. Read all about them here:

https://support.apple.com/en-us/HT201945