[genocidicbunny]

Comcast's list of approved devices includes (or used to at least) some of the more common Arris Surfboards; I also used one when I had Comcast service. You probably also used one that was 'compatible'.

[devmor]

The list of compatible devices was simply a list of all devices that supported DOCSIS 3.1 at the time.

At no point was my firmware swapped out, or anything of that nature.