Fault Reports
What Do the Modem Lights Mean?
September 16, 2026
3 min read
Technical Support Team
Light names differ slightly between models; the meanings below are common to most fibre modems.
The Lights
- Power: solid means the device is on. If it is off, check the adapter and the socket.
- PON / Fiber: solid green means the fibre line is connected. If it is blinking, the line is trying to connect; wait a few minutes.
- LOS: red means no fibre signal: the cable is unplugged, bent, or the line is down. Seat the fibre cable without bending it; if it persists, open a fault ticket.
- Internet: solid green means the internet session is up. Red means a username/password or session problem.
- WLAN / Wi-Fi: the wireless network is on. If it is off, the Wi-Fi button on the modem may have been pressed.
- LAN: a device is connected by cable.
What to Do
Switch the modem off for 30 seconds and back on. If LOS stays red or the Internet light stays off, note the state of the lights and open a fault ticket on 0850 308 19 99 — the ticket is resolved much faster with this information.