Router flashing red: what to check

A red light is a clue. Start with the label beside it.

The answer in 2 lines. Photograph the light and its label before changing anything. Check that your router and any separate fibre connection box have power, inspect accessible cables and restart the router following its instructions. Check for an outage through your provider using mobile data. If the connection stays down, report it and keep the reference. A visible Wi-Fi network does not mean your broadband connection is working.

The first checks

Record which box has the red light, the label beside it and whether it flashes. Photograph any displayed error message.
Check power switches and accessible plugs. With full fibre, check the separate wall-mounted fibre connection box as well as the router.
Restart the router using its instructions, then check whether another device can connect. Avoid repeatedly switching the equipment off and on.

Stop: danger

Do not open the fibre connection box or dismantle the wall socket. Ask your provider to arrange any necessary repair.
Do not press a recessed reset button unless the instructions for your exact equipment or your provider tell you to: restarting and restoring factory settings are different operations.

What does the red light mean?

There is no reliable diagnosis from colour alone. A power light, internet light and optical connection light describe different parts of the connection. Record the model and wording rather than telling support only that the router is red.

A separate fibre connection box is often called an ONT. A fault there can affect internet access even when the router still broadcasts your Wi-Fi network. Conversely, a problem affecting only a phone or laptop may be specific to that device. Try another device before assuming the whole connection has failed.

What you can check yourself

Look for a loose power lead or an accessible network cable disturbed during cleaning. Check connections against the original installation instructions; avoid swapping cables between unfamiliar sockets. Inspect the fibre cable without disconnecting it or pulling it tight.

For broadband through a telephone socket, support may ask you to connect at the main socket. Follow their instructions for your installation. Use Ofcom’s troubleshooting guide to work through power, restart and outage checks, then prepare the information needed to report a fault.

What not to do

Buying a replacement router before support has checked whether the incoming connection is working.
Treating an empty outage page as proof that your line is healthy.
Accepting an engineer visit without asking whether a charge could apply if the fault is in your own equipment.

Report the fault and ask about compensation

Use the contact details on your bill or existing account correspondence. Explain when service stopped, which lights changed and what you tried. Ask for a fault reference, the next update and any temporary connection available. Your retail provider handles the fault even where another organisation maintains the network.

For participating providers, Ofcom’s automatic compensation page lists eligibility and exclusions: check whether your service is covered. The published 2026 delayed-repair rate is £10.34 per qualifying calendar day once a reported total loss of service remains unfixed after two full working days. Problems caused by equipment or activity inside the home can be excluded.

If you need the connection for essential support

Tell support immediately if you rely on a care alarm, connected healthcare equipment or a digital landline without a usable mobile alternative. Ask about priority repair and a suitable backup. Read Ofcom’s digital landline guidance and use its checklist to explain your household’s needs. An internet-based landline may fail when broadband fails.

If the response remains unsatisfactory, make a formal complaint and retain it. GOV.UK’s service disruption guidance explains escalation: in 2026, independent dispute resolution is available after six weeks unresolved, or earlier with a deadlock letter. Ask your provider which approved scheme handles its complaints.

Good to know

Keep a photograph of the usual lights and save support details somewhere accessible without home broadband.
After service returns, leave equipment powered as recommended so it can receive automatic updates.
This guide covers England. The telecoms regulator’s framework also applies across Wales, Scotland and Northern Ireland; equipment and provider arrangements vary.

Illustrative example: after moving a cabinet, Sam notices a red light on the fibre box. He photographs it, checks the power and avoids opening the box. Support logs the fault and arranges the appropriate repair instead of asking him to buy a router.

A made-up story, for illustration.

Bobby

Sources, verification, confidence

Verified on 6 November 2026, for England. Confidence: high for reporting, compensation conditions and complaint escalation; medium for equipment checks because lights and restart procedures depend on the installation. No universal meaning is assigned to a red light.