Local outage or troubleshooting

Intermittent internet outage.
Router receives valid public IP ([Edited: "Personal Information"]) from Comcast but loses connectivity to assigned gateway ([Edited: "Personal Information"]).
Traceroute dies immediately after router.
Ping to Comcast gateway and DNS servers shows 100% packet loss during outage periods.
Issue affects all devices.
Suspect gateway hardware or DOCSIS signal issue. Request signal-level review and line testing.
Modem/Gateway is currently in bridged mode, which is necessary and needs to remain there for my network. Has been working perfectly until sometime in the last 8 hours.