I can’t login using the password that I just created when I did a hard reset to get to the pages to change my guest wifi passwords for security purposes. I have an Arris SBG8300

I did two hard resets now to try to solve it and it skips the username creation item and goes straight to the create a password and reenter password page which I completed. I then changed the name and passwords of my primary daily Wifis - but to access the guest wifi band pages - I need to login using the account info...On that side, it’s saying that I’m putting incorrect credentials (“admin” and my new password). I tried the new password from the initial steps, the new primary daily wifi password, and the number password on the back of router, I tried resetting the router again and doing it all again and no success….I validated they were all correct multiple times. Is there another username other than “admin”, perhaps? 

Thanks in advance!