Cannot access port forwarding options through Admin Tool or Xfinity App

Hello,

I have a XB3 model wifi router.  I have attempted to set up port forwarding with the admin tool by following the instructions here:

https://www.xfinity.com/support/articles/port-forwarding-xfinity-wireless-gateway

However, when I try to access the port forwarding options, the tool refers me to xfinity.com/myxfi, which then refers me to the Xfinity App.  So through the Xfinity App, I tried to go to the Port Forwarding options, but it displays the following error message:

"Something unexpected happened.  We can't display your details right now.  Please try again or come back later."

I doubt this is a temporary issue.  Can this be fixed and how?