Home / Fix guides / Router red light: what each colour actually … published 2026-03-12 · updated 2026-03-15

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Router red light: what each colour actually means

By Tasleem Akhtar | Senior Telecom Advisor | Updated 2026-03-15

A red or orange LOS/optical light means the fibre signal is not arriving; a red WAN light means the signal arrives but authentication to du failed; a red internet light with a green WAN usually means an IP/DNS problem on your side. Fixing the wrong one wastes a day, so identify the light first.

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Router red light: what each colour actually means

Do this, in order

Read the label next to the light: LOS, PON/Optical, WAN, Internet, Wi-Fi. PON solid green = line fine.
LOS red: check the thin fibre lead for a kink or a pulled connector, then reboot once. Do not open the ONT.
WAN red: your account may be suspended or the PPPoE credentials dropped - check for an unpaid bill or a recent plan change, then reboot.
Internet red with green WAN: forget the network on one device and reconnect; if every device fails, clone the DNS to 1.0.0.1 / 8.8.8.8 in the router LAN settings.
Send us a photo of the lights on WhatsApp and we will tell you which queue the ticket belongs in - fault, billing, or settings.