When the internet drops, the first thing support asks is “what colour are the lights on your router?”, and most people have never looked. Those little blinking icons are the quickest health check you have, and being able to read them turns a ten-minute guessing game into a thirty-second diagnosis. Here is what each one means and, crucially, what to tell support.
Reading the lights
Labels and colours vary by make, so treat this as the general rule rather than gospel, but across most business routers and fibre boxes it holds true.
| Light | What it is | Healthy | Trouble |
|---|---|---|---|
| Power | The unit has power | Solid | Off means no power or a dead unit |
| DSL / Broadband | Sync with the exchange (copper lines) | Solid | Flashing = trying to connect; off = no line |
| LOS | Loss of signal on a fibre line | Off | Red = the fibre signal is lost, report it |
| Internet / WAN | Connection to the outside world | Solid, often green | Off or red = no internet |
| LAN / Ethernet | A wired device is connected | Solid or blinking with traffic | Off = nothing plugged in or a bad cable |
| Wi-Fi / WLAN | The wireless radio is on | On, blinking with activity | Off = Wi-Fi disabled |
The two lights that matter most in a panic
When something is wrong, look at Internet / WAN and LOS first. If the Internet light is off or red but the broadband or fibre light is fine, the line is reaching you but the connection to the provider has dropped, often a fault at their end or a session that needs re-establishing. A red LOS on a fibre box is the big one: it means the fibre signal has been lost, which can be a cut, a fault, or simply the fibre cable being knocked out of the ONT. That is a report-it-now situation, not a reboot-and-wait one.
What to tell support
Do not say “the lights look wrong.” Say exactly what you see, because the colour and whether it is solid or flashing tells us a great deal:
- Name the light and its state. For example, “the LOS light is solid red” or “the Internet light is off but broadband is solid green.”
- Solid or flashing? A flashing sync light means it is trying and failing to connect; a solid one means it has connected. That difference points us straight at the cause.
- What changed? Power cut, building work, a cable knocked, or nothing obvious.
A thirty-second phone snapshot of the lights, with colours, saves everyone a diagnostic dance. It is the single most useful thing you can do before you call, alongside noting the time it started.
Before you call
Photograph or note the lights and their colours, and if the LOS light is red, check the thin fibre cable is firmly seated in the box, gently, it is delicate. If it is a general dropout rather than a red LOS, one reboot is worth a try, but know when a reboot is hiding a bigger problem. And whatever the cause, gather a few details first using our checklist on what to collect before reporting a fault.
How Synergy Max helps
Because we manage the line, we can often see what your router lights are telling us from our side too, which means a customer reading “solid red LOS” down the phone gets a straight answer and the right fix, not a script. It is all part of the support that comes as standard.