How to determine if my Gateway is xFi Advanced Security compatible?

For compatiability, see https://www.xfinity.com/support/articles/getting-started-with-xfinity-xfi-advanced-security.

They're portraying xFi Advanced Security as a complete replacement for Norton (see https://www.xfinity.com/support/articles/norton-security-online-sunset), but that's a gross exaggeration. For example, xFi gateways cannot detect threats that arrive in encrypted ("https") data streams. Only software running on the customer's computer or mobile device where the stream is decrypted can do that.

Users who relied on Norton should subscribe to the paid version or install another antivirus program or app to take the place of the AV program Comcast is dropping.