Hello @ComcastAlly , I need help with the same problems as the below forum. I too was on a long conversation with customer service - even with a level 2 specialist. I cited this same problem that was on the forum but came to a dead end. Called both Comcast and Arris. Please kindly help!
I bought the Arris SB8200 and trying to get the 2nd port with another IP address. I bought the Performance Plus Internet + Gigabit Internet.
First, check the "Rate Card" for your local area to see if that feature is even available anymore. Seems that it is being phased out;
It's a PDF.
Scroll down to "Xfinity Internet" and look for "Additional IP Addresses".
If nothing is listed then it's likely to have been discontinued in your local market area.