Xfinity Modem Solid Red Light: Meaning & Fix
Quick Conclusion
A solid red light on an Xfinity modem (e.g., XB6, XB7, XB8) indicates a critical failure in the boot process or a loss of downstream signal, often due to a hardware fault, ISP outage, or provisioning error. This is a severe status that typically prevents any internet connectivity and requires immediate troubleshooting.
Engineer's Pro-Tip
Xfinity XB7 and XB8 gateways have a thermal management system that can trigger a solid red light if overheating occurs; ensure the modem is placed in a well-ventilated area, at least 6 inches from walls, and away from heat sources to prevent false hardware failure indications.
Community FixReddit
"Sudden loss of connectivity to ISP - WAN light solid red on router"
Sounds like an ISP issue to me. Make a service call and see what they say.
Read original threadWhy is this happening?
- A hardware failure in the modem's internal components, such as a corrupted NAND flash or power supply issue.
- A complete loss of downstream signal from the coaxial cable due to a line break, loose connection, or ISP network outage.
- A backend DOCSIS provisioning failure where the modem cannot authenticate with Xfinity's network.
- An interrupted firmware update that has left the modem in an unbootable state.
Step-by-Step Fix Flow
Check for ISP Outage via xFi App
Open the Xfinity xFi app on your mobile device or visit xfinity.com/status. Look for service alerts in your area; if an outage is reported, wait for Xfinity to resolve it, as the red light may persist until service is restored.