This light shows whether your ONT is getting power. What to check: Make sure the power cable is securely plugged into both the ONT and a working wall outlet. The LOS light on your router indicates the status of your internet connection to the Internet Service Provider (ISP). If you're using a power strip, check. Underneath the box, from left to right, are 3 connectors – power, LAN out, optical fibre in, That middle one is the one that goes to your router. As you can see there are 4 lights at the top of the OpenReach Full Fibre modem – Power, LOS (Loss of Service or Loss of Signal), PON (Passive Optical. The LEDs on your modem, optical network terminal (ONT), router, or modem/router combo (gateway) are most likely blinking because they're communicating what the device is doing, or there's an error. All networking devices, like modems and routers, provide a row of status lights that represent the. Those blinking lights on your modem and router actually mean something important. Most of us have experienced the frustration of Wi-Fi cutting out during an important call or while streaming our. The tables in this article provide detailed information about the possible appearances of the LED lights on each device, the possible causes of each state, and what you should do.