What do the lights on my OpenReach Full Fibre modem mean? – The Big Tech Question

Congratulations! If you’re reading this then I’m guessing you’ve upgraded to Full Fibre, or FTTP (Fibre to the Premises) as it’s also known. With vastly superior speeds over traditional fibre broadband, it’s slowly rolling out across the UK.

One aspect of the installation is a wall mounted modem (known as an ONT – Optical Network Terminal), which goes between the fibre connection outside and your router. No matter which ISP you’re with, OpenReach will have installed this for you and it will be one of their branded boxes.

They’ve gone through a number of different models but, right now, are installing a compact little box made by Nokia. This is what it should look like…

Yes, this is mine.

Underneath the box, from left to right, are 3 connectors – power, optical fibre in, LAN out. That last one is what 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 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 indicating your connection at the other end of the network.

Here’s what those lights really mean…

LightStateWhat it meansPowerOnThe ONT has powerPowerOffThere is no power to the ONT. Check the power cable is properly in (the one on the left-hand side) and that the mains connection on the other end is switched on.LOSOffYou have a working fibre connectionLOSOnYou have a fibre connection issue – check the fibre connection in the bottom of the ONT.PONOffNo network connection has been made.PONOnYou have a working network connection. PONFlashingThe ONT is negotiating a connection on the network. You’ll find this might happen a few times after initial installation.LANOffThere is no data transmitter to your router – check the LAN cable!LANFlashingThe shows that data is transmitting successfully to your router

So, a full working connection should look like this…

LightStatePowerOn solidlyLOSOffPONOn solidlyLANFlashing

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