What is the exact make and model number of the modem ?
It's getting harder to access that site due to browser security. You can install the "Xfinity " app onto your cellphone instead, but it's still not everything you used to have from the browser.
Attempts to access this address come up unsucessful. Trying to access modem settings to change password.
O/k try using http://10.0.0.1
admin is the default username and password is the default password
Quite welcome !