Router and Wi-Fi problems

Before touching anything, look at the box. Router status lights are a genuine diagnostic display that most people have never learned to read, and they separate the two things that get confused constantly: The Wi-Fi inside your home, and the internet connection coming into it.

The lights

Names vary by manufacturer, but the categories are consistent.

The critical distinction is between the line light and the internet light. Line light off means the physical connection to your provider is not there - That is theirs to fix and nothing you do will help. Line light on but internet light off means the physical line is fine and the session is not being established, which is often authentication and sometimes an ISP-side fault.

Colours

Broadly consistent across manufacturers: Green or white is working, blinking is trying to establish, orange or amber is connected but degraded, red is failed, off is disabled or dead.

On a cable modem, a blinking or orange downstream light means it cannot lock onto a channel - A signal problem on the coaxial line, which affects the whole node and is worth reporting. On fibre, a red LOS light means loss of signal on the optical line, which is either a cut or a problem at the exchange.

Wi-Fi problems are not internet problems

These get conflated constantly and have completely different fixes.

Wi-Fi problem: Connected to the network, no internet; some devices work and others do not; it is fine near the router and terrible upstairs; speed drops when the microwave runs.

Internet problem: Every device fails equally, wired included; the line or internet light is wrong; your neighbours on the same provider are also affected.

The decisive test is a cable. Plug a laptop directly into the router with Ethernet. If that works, the line is fine and your problem is entirely the radio. If it does not, the radio is irrelevant.

Fixing Wi-Fi specifically

Channel congestion

The 2.4 GHz band has three non-overlapping channels and is shared with microwaves, Bluetooth, baby monitors and every neighbour. In a flat block it is frequently unusable in the evening.

Use 5 GHz where you can - Shorter range, far less congestion, much higher throughput. Most routers broadcast both bands under one name and let devices choose, which usually works and occasionally leaves a device clinging to a weak 2.4 GHz signal when a strong 5 GHz one is available. Separating the bands into two named networks gives you control over that.

Placement

Wi-Fi is absorbed by water and blocked by metal. A router in a cupboard, behind a television, on the floor or next to a boiler is being deliberately handicapped. Central, elevated and in the open is worth more than almost any equipment upgrade.

Too many devices

Each connected device consumes airtime whether it is doing anything or not. Thirty smart devices, cameras and phones on one access point will degrade it noticeably, and consumer routers handle this less gracefully than their specifications suggest.

Restarting properly

It genuinely fixes some problems - A stuck DHCP lease, a full NAT table, a firmware bug, a cached DNS answer. Done wrong it fixes none of them.

1. Unplug the router from power.
2. Wait thirty seconds. This matters: It lets capacitors discharge and lets the ISP's session time out at their end. A two-second cycle often reconnects the identical broken session.
3. Plug in and wait two to five minutes for full sync. Fibre and DSL take longer than cable.
4. If there is a separate modem, power the modem first, wait for it to sync, then the router.

When it is intermittent

Intermittent faults are almost always physical or capacity-related rather than configuration.

Same time every evening points at congestion on a shared medium - Your neighbours, not you. Random drops that correlate with weather suggest water in a cable joint, which is common on older copper. Drops when a particular device joins suggest an IP conflict or a device with a broken network stack. Progressive degradation over weeks suggests failing hardware, and routers do die slowly.

When to stop and call the provider

Call when the line light is off or red, when the fault persists after a proper restart and a wired test, when it is clearly intermittent over days, or when other people in your area are reporting the same thing.

Before calling, gather: Which lights are wrong, whether a wired connection works, how long it has been happening, and what you have already tried. It shortens the call considerably and skips the script.