Is your ONT Service, Alarm or Power light off/red, or PON/Broadband flashing red/off? Restart your ONT, disconnect the power cable for at least a minute before reconnecting it. Wait for around 2 minutes for the ONT to come back online to see if the lights no longer indicate an. 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 Network) and LAN (Local Area Network – but you know this one, right?). Think of LOS as showing a cut in the fibre connection, whereas PON is. Learn what each light on your fiber equipment means—from power and fiber signal to Ethernet and phone service—and how to quickly troubleshoot issues. This light shows whether your ONT is getting power. Verify that the power outlet is working by plugging in another device. Check the ONT's power button (if applicable) to. If your router light is flashing, this means that the service is initialising or that data is being exchanged (i. A red light or light (or if the light. Router status lights, often referred to as LED indicators, are small lights on the front panel of your router. Typically, these lights correspond to various router functions such as power. A white Cityfibre ONT in working order should have a green "Power" and "PON" lights, the "Alarm" light should be off, and the "Data" light, however, could be a different color depending on the service you have, which can be either one of the following: Is your ONT power light off? Check that the.