When the Orbi came from the factory, the web login credentials were "admin" and "password". During the initial setup, the user is made to change the password to some other value. If this new password was not recorded there are two options:
When an incorrect password is entered three times in a row, a Password Recovery option is provided where the user can enter the router serial number and answer some security questions that were supposed to have been defined during the original setup. If those were not defined or the responses do not match exactly, then the only other option is to perform a Factory Reset.
