What do all the sockets and buttons on the back of a router do?

A router quietly does two unrelated jobs — connecting to the line, and running the network inside the house — and its back panel reflects that split. Almost every confusing router problem comes from not knowing which side of the panel you are on, and the sockets look near enough identical to make the mistake easy.

Step by step

1. Identify the socket that faces the outside world.On part-fibre it is a small socket labelled DSL or BROADBAND taking a thin cable to the phone master socket. On full fibre or cable it is an ethernet-shaped socket labelled WAN or INTERNET, taking a cable from the wall box. It is usually a distinct colour and it sits slightly apart.
2. Recognise the LAN sockets as one group.Typically four, all identical and interchangeable, for wiring devices directly. Any device that never moves — the television, a desktop, a console, a printer, a mesh node — is better here than on wifi.
3. Understand what a wired connection actually gains.It is faster, it never drops, and it takes that device off the wireless entirely, which leaves more of the wireless for the phones and laptops that have to move. On a household with a lot of devices this is the cheapest improvement available.
4. Know what the telephone socket is now for.On a digital voice service the handset plugs into the router rather than into the wall. That socket is usually smaller and marked with a handset symbol. It also means the phone stops working in a power cut unless a battery backup unit is fitted.
5. Treat the USB socket as optional.Where present it shares a printer or a drive across the network. It is convenient and generally slow, and it is not a substitute for a proper network drive if the household is storing anything important on it.
6. Understand the WPS button before using it.It pairs a device without typing the password, by putting the router into an open pairing state for a couple of minutes. Convenient for a printer; worth turning off afterwards, because it is a known weak point.
7. Learn the difference between the power switch and the pinhole.The power switch restarts the router and changes nothing. The recessed pinhole is a factory reset: it erases the wifi name, the password and every setting, so every device in the house has to be rejoined by hand. It is a last resort, never a first step.
8. Note the wifi on-off control if there is one.Some routers have a physical button or a switch that disables the wireless entirely. It is an occasional cause of a mysterious total wifi failure, particularly in a house with children or a router within reach of a hoover.
9. Write your wifi name and password somewhere before you need them.They are printed on a card or a label on the router, which is unreadable once the router is behind furniture and gone entirely if it is ever reset. A photograph of that label is two seconds of work.

Tips

• If the router has to sit somewhere awkward for the line, a long ethernet cable from a LAN socket to a mesh node elsewhere is usually a better answer than moving the router.
• Label each ethernet cable at both ends. A router with four identical black cables is impossible to work on later.
• Provider-supplied routers sometimes have fewer LAN sockets than people expect. A small unmanaged network switch plugged into one LAN socket adds several more for very little money.

Common mistakes

• Putting the incoming line into a LAN socket — The router then works perfectly on its own network and has no internet at all, which is a genuinely confusing symptom. The line has exactly one correct socket.
• Using the pinhole reset to fix a slow connection — It does not touch the line, and it costs you the wifi name and password plus an evening rejoining every device in the house. Restart with the power switch instead.

If it doesn't work

Questions people ask