This is just something to be beware of so that you do not get stuck in a loop.
After a DrayTek Vigor 2830 had been factory reset we still could not login - none of the passwords would work!
As we can see from the above it should be admin and admin but from Microsoft Edge on Windows 10 nothing would work.
After a few tries we did notice that the response from admin/admin was considerably slower than the other options and....
Yes, you guessed it, the Microsoft Edge browser just bounces back to the login page even when the login is correct.
We didn't try adding the router logon site to the compatibility view as an option but no doubt that would work. As it was we just used Google Chrome instead.
As an aside the Google Chrome option doesn't work on the 2830 and older certificates for SSL login so stick to Firefox or good old-fashioned IE for that.