1 November 2026

The Openreach ONT is the device that converts the incoming fibre optic cable into a regular copper data service that your router can use. Openreach opted to use an external device to perform this function, rather than make each router vendor have to create a new model with the optical unit inside. The lights on the ONT go some way to indicate what the state of the fibre connection is.

The image above shows ’normal’ condition - the ONT has power, is connected to the exchange (PON) and connected to the router (LAN).

Typical Errors

• All indicators are off

  • Check power supply is plugged in at the wall and the cable is fully inserted into the ONT.

• ‘LOS’ is showing red, ‘PON’ is off

  • This usually indicates an error on the fibre side. Sometimes it is purely that the fibre connector hasn’t locked into place on the bottom of the device, but usually it means a break in the fibre.

• ‘LAN’ is off, ‘Power’ and ‘PON’ are green

  • Check the cable between the ONT and the router, and that the router has power.

Fault Reports

When we log a call with Openreach we will be asked for your contact details and also some idea of availability, should they need to come into the property.

We will usually request the ’earliest appointment’, which is typically the next working day, but depends on the availability of their engineers.

If the damage to the fibre is within the curtilage (boundary) of the property and is clearly not a defect on their equipment, you will be charged for the repair.

In simple terms, if you accidentally cut through the incoming fibre on your house, or a branch on your tree breaks the fibre, then they will charge. If it’s a tree down the road on public/council land, then they won’t.

← All Tech Hub articles