Engadget explains the difference between WAN and LAN ports

The distinction becomes most important when setting up a new router or adding devices to an existing network. Many devices, including TVs, gaming consoles, and PCs, benefit from a wired connection for faster speeds and stability, but plugging one of them into the wrong port can prevent internet access, Engadget notes.

LAN stands for Local Area Network and refers to the network created entirely within a home or local environment. Devices connected to a router are automatically added to this network, allowing them to communicate with each other. Features such as Apple's AirPlay, Google Cast, and Roku's screen mirroring depend on this local connectivity. WAN, short for Wide Area Network, is the physical link to the outside world, typically the internet. The WAN port is where the cable from an internet service provider is plugged in, and with proper configuration the router negotiates an internet connection over that port, routing traffic from LAN devices to the internet.

The router assigns each device a private IP address while receiving its own IP address from the upstream internet service provider's network, effectively acting as a bridge between the local network and the wider internet. Some router brands use different colors to distinguish WAN from LAN ports, and LAN ports are often numbered; the order of numbered ports usually does not matter, though some devices offer a few faster LAN ports, so checking the manual is advised for maximum throughput.

Wi-Fi is essentially another way of connecting devices to the local network, using a wireless link instead of an Ethernet cable. Devices remain connected to Wi-Fi even when the internet stops working because the wireless link only connects local devices, including the router that negotiates internet access over the WAN port. Without internet, users can still access networked printers or storage servers over the local network. Modern routers often support guest Wi-Fi, which creates a secondary LAN that allows internet access but isolates guest devices from the primary local network, adding a security measure against attacks on vulnerable devices. Mesh Wi-Fi systems and access points can also extend the LAN beyond physical ports, either via cable or wirelessly.

The explainer advises that remembering the difference is simple: the WAN port connects to the internet, while LAN handles communication between local devices. Choosing the right port becomes less daunting once that distinction is clear.