LAN Cable to WiFi Router: Which Port and Which Cable

October 29, 2026

Quick Answer: Plug the incoming service into the WAN or Internet port, usually a differently coloured socket, and plug computers, switches and access points into the LAN ports. Use a Cat5e or Cat6 patch cable, keep runs under 100 m, and do not connect two LAN ports of different routers together unless one is deliberately running in access point mode. Most “no internet after connecting a cable” cases are a cable in the wrong socket.

A home router is two devices in one housing: a router that separates your network from the provider’s, and a switch that fans the inside network out to several sockets. The WAN port belongs to the first, the LAN ports to the second, and swapping them produces a network that either has no internet or has two competing DHCP servers.

Which Socket Does What

Connection	Port on the router	Cable	Result if wrong
Modem or ONT	WAN / Internet	Cat5e or Cat6 patch	No internet, LAN light only
Desktop PC	LAN 1 to 4	Cat5e or Cat6 patch	No link or no address
Second router as access point	LAN to LAN, AP mode on	Cat5e or Cat6	Double NAT, roaming breaks
Network switch	Any LAN port	Cat5e or Cat6	Nothing, switches are automatic

Straight-through is all you need

Every port on a modern router, switch or computer implements automatic crossover detection, so a standard patch cable works in every combination. Crossover cables belong to equipment built before roughly 2005 and to a few industrial devices. The wiring standard inside the plug, T568A or T568B, only has to be consistent at both ends; a cable wired A on one end and B on the other is a crossover and will usually still work, which is why cheap cables pass tests and confuse people.

Cable choice in one line

Cat5e carries gigabit to 100 m and costs very little. Cat6 does the same with better margins and supports 10GBASE-T to about 55 m. Cat6a extends 10GBASE-T to 100 m and is stiffer. For a router-to-device patch lead, Cat6 is the pragmatic default because it also survives the next speed upgrade without being replaced.

Double NAT and AP Mode

Two routers in series, each doing address translation, break port forwarding, game hosting, some VPNs and printer discovery. The fix is to disable DHCP on the second device and connect it LAN to LAN, so it behaves as a switch with a wireless access point attached. If the second device has an explicit access point or bridge mode, use it and let the first router keep all the routing. Where the second router must stay a router, put its WAN port on the first router’s LAN and accept double NAT deliberately.

Practical Scenarios

Extending coverage to a back room: run one cable from a LAN port to an access point in the far room instead of repeating wirelessly; the cable carries the full speed.
New fibre installation: ONT to WAN with a short patch, then the provider’s router to a switch if more than four wired devices exist.
Office with more than four wired desks: add a switch on one LAN port and keep the router for routing; hub vs switch vs router explains where each belongs.
Gaming console that keeps dropping: a wired ethernet cable for the WiFi router removes the wireless variable entirely.

Checking the Link

Read the port LEDs before touching configuration. No light at either end means a dead cable, a dead port or a device that is off; the link light proves the physical layer and nothing more. A light but no internet points at addressing, so check whether the device received an address in the same subnet as the router. A gigabit port that negotiates 100 Mbps is nearly always a damaged pair or a plug with a stray wire, and a tester that reports wiremap will find it in seconds. For long runs, use a Cat6 LAN cable rated for the distance rather than joining three short leads with couplers.

Runs, Plates and Wall Sockets

Where the cable disappears into a wall, terminate it on a keystone jack rather than pulling a loose lead through a hole. A jack protects the solid-conductor cable from movement, gives a testable point, and lets a patch lead take the wear. Keep 30 cm of slack at each end, avoid tight staples that crush the pair geometry, and leave at least 10 cm from mains cable where the two run parallel. In a rented property, a flat cable under a carpet edge is a reasonable temporary answer as long as it is not walked on; in an office, put it in trunking. If a run must pass between buildings, use fibre or accept that copper will eventually take a surge on the network port.

FAQ

Does it matter which LAN port I use?

No. All LAN ports on a consumer router are equivalent unless one is labelled for IPTV or gaming, in which case the label may apply a VLAN for the provider.