Unable to access Advance Call Forwarding: it says "Sorry, but something went wrong. Please try again in a few minutes"

I need to access Advanced Call Forwarding to change the number of rings so my home voice mail will take the message and also to activate NoMoRobo.  However, on the Call Forwarding page, the Advanced Call Forwarding option flashes to "Sorry, but something went wrong. Please try again in a few minutes".  This happens both on the Windows website and the Android App.  I am the Primary, and only, user of the account.  This is a deal-breaker for switching to Xfinity.  I see from browsing the internet that many many people have this problem.