For folks following this here - node and neighborhood look clean. The issue appears to be a failing cable modem (MB8611 - they seem to suffer frequent disconnects when they fail). We have suggested the customer replace the modem ASAP and we will re-run all the DOCSIS diagnostics. Suitable alternative COAM modems are listed at https://old.reddit.com/r/Comcast/comments/1kg99v3/buying_you...
- Jason (I work at Comcast)