This white box connects to a fibre‑optic cable that runs directly to your property and gives you access to our fibre broadband and voice services. The ONT has several lights on the front. When these lights change colour or start flashing, it usually means something is happening with. The lights on your ONT are typically LED indicators that display different colors and patterns to convey information about the device's status. 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. This guide is designed to offer an explanation of the lights seen on the most common Full-Fibre (FTTP) modems fitted by Openreach - sometimes called an ONT. The lights on your Fibre Connection Box let you know when everything's working as it should be and can tell you what's wrong if you're having problems. If you need help finding your ONT, look for a small black/grey or white box, mounted to a wall within your property (usually on the ground floor). A black/grey Cityfibre ONT in working order should have a green (or flashing green) "Ethernet" light and green "Power", "Broadband", and "Service".