After some gnashing of teeth I decided to go out and buy a new cable modem and have it provisioned as new service. Lo and behold! I have Internet access at home again. While I had the technician, I had him look through the systems. As I suspected, Comcast never provisioned my old cable modem correctly. It was listed in “one system” as a TV cable box and in “another system” as a cable modem. Evidently that contention caused me to constantly lose connection.
So after months of constantly dropping service, of more than a dozen technician visits, and over 60 phone calls to Comcast, it was their system – as I suspected all along.
Comcast, how I loathe thee.