
Few things are as frustrating as your internet going down, especially when you notice the ominous red blinking LOS (Loss of Signal) light on your router. This guide will walk you through what the LOS light means, why it blinks red and step-by-step instructions on how to resolve the issue, including resetting your router.
What Does the LOS Light Indicate?
The LOS light on your router indicates the status of your internet connection to the Internet Service Provider (ISP). When it’s green and steady, everything is fine. However, when it blinks red or stays solid red, it signifies a Loss of Signal, a problem preventing your router from communicating with the ISP.
Why Is the LOS Light Blinking Red?
Several reasons can cause the LOS light to blink red:
- Fiber Optic Cable Damage: A physical cut or bend in the fiber optic cable can disrupt the signal.
- Service Outage: ISP maintenance or a local service outage can interrupt your connection.
- Loose or Damaged Connections: Improperly connected cables or faulty connectors can lead to a loss of signal.
- Faulty Router: A malfunctioning router or Optical Network Terminal (ONT) could be the culprit.
- Power Issues: Fluctuations in power supply may disrupt the router’s ability to function.
What to Do When the LOS Light Blinks Red
1. Check for Local Outages
Before you dive into troubleshooting, check if your ISP is experiencing a service outage:
- Contact your ISP via phone or app.
- Check their website or social media pages for updates on outages.
2. Inspect the Fiber Optic Cable
- Look for physical damage, cuts, or bends in the fiber optic cable.
- Ensure the cable is properly connected to the router’s WAN/ONT port.
3. Reboot Your Router
Rebooting is the simplest and often the most effective solution:
- Turn off the router.
- Unplug it from the power source and wait for 30 seconds.
- Reconnect the power and turn it back on.
- Check if the LOS light turns green.
4. Check Cable Connections
- Ensure the power cable, LAN cable, and fiber optic cable are securely connected.
- If any connectors seem loose, tighten them gently but firmly.
5. Contact Your ISP
If the above steps don’t resolve the issue, it’s time to involve your ISP. Provide them with the following details:
- LOS light status (blinking or solid red).
- Any observations about the cables or router.
- Your account details for faster service.
How to Reset Your Router
If rebooting and other checks don’t work, resetting your router may resolve the issue. Follow these steps carefully:

1. Locate the Reset Button
- The reset button is usually a small hole labeled Reset on the back or underside of the router.
2. Prepare for Reset
- Ensure you know your ISP-provided credentials (PPPoE username and password). A reset will erase all custom settings.
3. Perform the Reset
- Use a paperclip or pin to press and hold the reset button.
- Hold the button for 10-30 seconds until the router restarts and the lights blink.
- Release the button and wait for the router to fully reboot.

4. Reconfigure the Router
- Log in to the router’s admin panel via a browser (commonly at 192.168.0.1 or 192.168.1.1).
- Enter the default username and password (found on the router or manual).
- Re-enter your ISP settings (if needed).
Preventive Tips to Avoid Future LOS Issues
- Handle Cables Carefully: Avoid bending or stretching the fiber optic cable.
- Invest in a UPS: Protect your router from power fluctuations.
- Regular Maintenance: Periodically check your cables and connections.
- Keep the Router Ventilated: Avoid overheating by placing it in a cool, open space.
- Stay Updated: Ensure your router firmware is up to date.
When to Replace Your Router
If the LOS issue persists despite all troubleshooting efforts, your router or ONT device may be faulty. Contact your ISP to confirm and request a replacement if necessary.
The LOS light blinking red is a common yet solvable issue. By following the steps outlined above, you can identify the root cause, fix the problem and restore your internet connection. Always handle your router and cables with care and don’t hesitate to contact your ISP for assistance if needed.