I ran into this problem since about 3 weeks ago.
Disconnect at random intervals, about 2~10 mins/time.
Then re-connect (auto or manually) after 3~30sec.
Any troubleshooting on my laptop didn't help.
My friend nearby said he ran into the same problem.
It seemed that this problem came from Xfinity gateway/router.
In the past hour, I've been kicked off a VPN to work every 10 minutes, on the 10 minute mark, for 30 second each time.
This is annoying for the VPN work, but really disruptive for our kids in online, live classes and my kid taking job interviews this week.
There seem to be many, many threads on this same behavior on this community forum and reddit. No answers from Comcast personnel that I can find.