I replaced the router and the fiber optic light is red

A red fiber optic (LOS) light indicates a loss of signal between your router and your ISP, often caused by cable issues, service outages, or router misconfiguration.

Understanding the Red LOS Light

The LOS (Loss of Signal) light on your router signals that the device cannot communicate with your Internet Service Provider (ISP). A solid or blinking red light typically means the router is not receiving a proper signal from the fiber optic line, which can result from a damaged cable, loose connections, ISP outages, or a faulty router .

Step-by-Step Troubleshooting

1. Check for ISP Outages
   • Visit your ISP's website or social media pages to see if there is a known service outage in your area. Sometimes maintenance or technical issues can temporarily disrupt your connection .
2. Inspect Fiber Optic Cables
   • Examine the fiber optic cable for visible damage, kinks, or sharp bends. Ensure it is securely connected to the router's WAN/ONT port. Avoid bending the cable tightly, as fiber optics are sensitive to stress .
3. Verify All Connections
   • Check that the power cable, LAN cables, and fiber optic cable are firmly seated. Loose or improperly connected cables are a common cause of signal loss .
4. Power Cycle Your Router
   • Turn off the router and unplug it from the power source for about 30–60 seconds. Reconnect the power and turn it back on. This can often resolve temporary connectivity issues .
5. Check Router Configuration
   • Ensure your router's WAN settings match your ISP's requirements. Misconfigured settings or outdated firmware can prevent the router from establishing a connection .
6. Factory Reset (Last Resort)
   • If the red light persists, perform a factory reset using the router's reset button. Note that this will erase custom settings, so you may need to reconfigure your network afterward .
7. Contact Your ISP
   • If none of the above steps work, the issue may be with the ISP's equipment or the fiber line outside your home. Contact your ISP for further assistance .

Key Tips

• Never look directly into a disconnected fiber optic cable end.
• Avoid bending fiber cables beyond the minimum bend radius.
• Keep your router in a well-ventilated area to prevent overheating, which can affect performance . By following these steps, you can often identify and resolve the cause of the red LOS light and restore your internet connection.