Troubleshooting Your ONT (Optical Network Terminal)
Your ONT (the little box on your wall) turns CityFibre or Openreach fibre into the blazing-fast Brillband connection. Different partners use different models, but the basics are the same: solid green LED's mean you’re good to go. Here’s how to keep yours in tip-top shape.
Which ONT Do You Have?
CityFibre usually fits Calix ONTs (e.g. Calix 801G/801GT) or Nokia XGS-PON units. Check coverage at cityfibre.com/coverage.
Openreach tends to install Huawei EchoLife (e.g. HG8010H5-20) or Nokia XS-010-X-Q for XGS-PON. Check coverage at openreach.com/full-fibre-broadband-checker.
LED Lights Cheat-Sheet
LED # | Label | What “Solid Green” Means |
1 | Power | ONT is powered up correctly. |
2 | PON/Broadband | Fibre link to the exchange is live. |
3 | Alarm/Service | Your Brillband service is active. |
4 | LAN/Ethernet/Data | Router is plugged in and talking. |
If any LED is off, flashing or amber, follow the steps below.
Quick Fixes for Any ONT
Check the Basics
Make sure the ONT’s power adapter is firmly seated in the wall and the ONT itself.
Confirm your Brillband router is plugged into the ONT’s Ethernet port (only one device belongs here).
Power-Cycle
Unplug the ONT’s DC lead, wait 30 seconds, then plug back in.
Give it up to 5 minutes to re-sync all LEDs to solid green.
CityFibre-Specific Tips (Calix & Nokia)
Alarm LED On (Calix) or Alarm/Service LED Off (Nokia)
Check the external fibre junction box for kinks or visible damage.
Power-cycle the ONT once.
Still in alarm? Email us or raise a ticket so we can escalate to CityFibre.
LAN/Ethernet LED Off
Swap in a known-good CAT6 cable and confirm you’re using the correct port.
Openreach-Specific Tips (Huawei & Nokia)
PON/Broadband LED Flashing or Off
Ensure the fibre connector is fully clicked home.
Gently wipe the connector end with a dry, lint-free cloth.
Power-cycle and wait up to 5 minutes.
LOS (Loss of Signal) LED On (Huawei) or Alarm LED On (Nokia)
Inspect the street-side drop cable, if it looks intact, power-cycle and then shout for help via live chat so we can liaise with Openreach.
Still not green? Our support team is on standby to sort out any partner-related ONT dramas, just hit our live chat. 🧑💻