I have the exact same problem. Mine only drops for about 30 seconds, but it's enough that my VPN drops and kills everything I'm working on; I also work from home and this is unacceptable. I was thinking of paying to get the ethernet cable run upstairs to my home-office, but from your experience, this may be a waste of money.
Xfinity has already been out once to change out the modem or router, didn't help one bit.
