FWIW, from the website, see the second bullet point;
"How can visitors connect to Xfinity WiFi in my home?
I am trying to give access to my guest when they come and visit me. However, i really hate giving access to my personal network. What are my options?
Your options are:
If you're using a Comcast gateway,
1. Create a secondary , restricted account for your guest to allow them access to the hotspot.
2. Get yourself a third party wireless router (doesn't have to be top of the line), hook it up to your gateway, configure it as a Wireless Access Point only (no routing functions) with a different SSID and password, and turn on AP Isolation. (Check router documentation on how to do this).
If you are using a third party wireless router,
1. Set up a Guest Network on that router. (Check router documentation on how to do this.)