What Does LOS Mean in Wi-Fi?

December 30, 2025

What Does LOS Mean in Wi-Fi?

If you’ve ever checked your router or modem and noticed a blinking red light labeled LOS, you’re not alone. Many users panic when they see it, assuming something is seriously wrong with their internet connection. But what does LOS actually mean in Wi-Fi, and should you be worried?

Understanding LOS can help you quickly identify connection issues and know when to troubleshoot at home versus when to contact your service provider.

What Is LOS?

LOS stands for “Loss of Signal.”

It indicates that your modem or Optical Network Terminal (ONT) is not receiving a proper signal from your internet service provider.

LOS is commonly seen in fiber broadband connections, where data travels through optical fiber cables rather than traditional copper wires. When the signal between the ISP’s network and your home device is interrupted, the LOS light turns red or starts blinking.

It’s important to note that LOS is not a Wi-Fi issue inside your home, but rather a signal issue between your provider and your modem.

Where Do You Usually See the LOS Light?

The LOS indicator typically appears on:

  • Fiber modems
  • Optical Network Terminals (ONTs)
  • Fiber routers provided by ISPs

It usually lights up in red or blinking red, signaling that the fiber connection has been disrupted. This is different from Wi-Fi lights, which indicate wireless activity inside your home.

Common Reasons for LOS in Wi-Fi Connections

Several factors can trigger a Loss of Signal. Some are temporary, while others require professional attention.

1. Fiber Cable Damage

Fiber cables are delicate. Physical damage caused by construction work, bending, or accidental cuts can interrupt the signal completely.

2. Loose or Disconnected Fiber Patch Cord

If the fiber cable connected to your modem is loose or unplugged, the signal won’t reach your device. Even slight movement can sometimes cause disconnection.

3. Power Outages or Network Maintenance

Planned maintenance or unexpected power issues at the service provider’s end can temporarily stop signal transmission.

4. ONT or Modem Issues

Hardware malfunctions, overheating, or internal faults in the ONT can also trigger LOS warnings.

5. External Network Problems

Issues at the ISP’s distribution point, splitter, or central office can affect multiple users in the same area.

What LOS Is Not

Many users confuse LOS with slow Wi-Fi or poor signal inside the house. LOS does not mean:

  • Weak Wi-Fi coverage
  • Router placement problems
  • Too many connected devices
  • Slow browsing speeds

If the LOS light is on, your internet connection is usually completely down, not just slow.

What You Can Do When LOS Appears

Before calling customer support, try these basic checks:

  • Ensure the modem or ONT has proper power supply
  • Check that the fiber cable is firmly connected and not bent sharply
  • Avoid unplugging or cleaning the fiber tip, as it is sensitive
  • Restart the modem once and wait a few minutes

If the LOS light remains red after these steps, the issue is likely outside your home.

When to Contact Your ISP

You should contact your internet service provider if:

  • The LOS light stays red for more than a few minutes
  • Multiple restarts don’t resolve the issue
  • You notice physical damage to the fiber cable
  • Neighbors using the same provider also face outages

ISP technicians are trained to inspect fiber lines, connectors, and network points safely.

How to Prevent LOS Issues

While not all LOS problems are avoidable, a few precautions can help:

  • Keep fiber cables away from foot traffic and sharp bends
  • Avoid moving or adjusting the ONT unnecessarily
  • Use a stable power source to prevent sudden shutdowns
  • Schedule professional relocation if you need to move the router

These habits reduce the risk of accidental signal loss.

Conclusion

LOS, or Loss of Signal, is a warning that your fiber connection has been interrupted between your home and your service provider. While it may look alarming, understanding its cause makes it easier to respond calmly and correctly. In most cases, LOS issues require technical assistance rather than changes to your Wi-Fi setup.

For users in Kerala, Asianet Fiber offers responsive customer support and a strong fiber infrastructure to ensure signal issues are addressed quickly and connectivity is restored with minimal disruption.