Not All Router Ethernet Ports Are Interchangeable, Engadget Guide Says

According to Engadget, if a router connects to a separate modem or optical network terminal, the cable from that device normally plugs into the router's WAN or Internet port. WAN stands for wide area network and represents the router's connection to an internet service. Router/modem combo units do not need this connection because one device performs both functions.

The other Ethernet connections are generally LAN, or local area network, ports. These are used for devices inside the home, such as a desktop PC, game console, smart TV or network-attached storage. Four LAN ports do not provide four separate internet connections, the guide says; they allow up to four wired devices to connect directly instead of using wireless connections. Some routers have ports marked WAN/LAN that can perform either job, while other models use auto-sensing Ethernet ports instead of a dedicated WAN jack. If a router does not clearly identify an Internet or WAN port, its setup guide or specifications should tell the user which port to use. If more LAN ports are needed, an Ethernet switch can add connections without requiring another router.

Not every LAN port on a router offers the same speed. Some routers have identical LAN ports, while others mix gigabit and multi-gigabit connections on the same device, as the Netgear Orbi 870 does, according to Engadget. Labels such as 1G, 2.5G, 5G and 10G refer to maximum link speeds of 1Gbps, 2.5Gbps, 5Gbps and 10Gbps. Manuals or specification sheets may use Ethernet standard names such as 1000BASE-T for 1Gbps, 2.5GBASE-T for 2.5Gbps and 10GBASE-T for 10Gbps.

The guide points to the TP-Link Archer BE900 as an example of why checking matters. That router has four 2.5Gbps LAN ports as well as 10Gbps connections that can handle either WAN or LAN duties. Engadget says there is no general rule that port 1 is faster than port 4 because of its position or number. If all LAN ports support the same speed and none has a special function, moving a device to a different port generally will not make the connection faster. The choice starts to matter when ports have different speed ratings or roles.

A faster Ethernet port will not make a slower device faster. Engadget says a 10Gbps port does not automatically give every connected device a 10Gbps connection because the rest of the Ethernet hardware must support the faster speed as well. If a computer has a 1Gbps Ethernet adapter, connecting it to a faster multi-gigabit router port does not upgrade what the computer offers. Copper Ethernet hardware typically uses auto-negotiation to determine a link configuration supported by both ends, so a 1Gbps device cannot become 2.5Gbps-compatible merely because the router port is faster.

The reverse also applies. When a computer with 2.5Gbps Ethernet is connected to a 1Gbps LAN port, the slower port becomes the limiting factor. To establish a faster link, the router port, the Ethernet interface on the connected device and the cable between them all have to support the higher standard. Engadget notes that cable names can cause confusion: Cat5e, Cat6 and Cat6A are cable categories, not router port speeds, so there is no such thing as choosing a "Cat6 port" on a router. Cable category, quality, length and installation can all affect which Ethernet speeds a setup will reliably support.

The guide also says an internet plan is not necessarily the limit for everything done over Ethernet. Two devices communicating inside a home on a LAN do not need to send that traffic through the internet connection. A PC and a network-attached storage device connected over 2.5Gbps Ethernet, for example, can transfer files across the local network at speeds far faster than a broadband connection likely supports. Before plugging a device into a router, Engadget advises checking the port's label, what speed the device supports and which Ethernet cable is used.

Editor's Summary

Engadget's guide explains that router Ethernet ports serve different roles, with WAN or Internet ports linking to a modem or fiber terminal and LAN ports connecting in-home devices. It also notes that LAN ports can have different speed ratings, and that actual link speed depends on the router port, the connected device and the cable. The practical takeaway is to check port labels and hardware capabilities before assuming a faster port will improve performance.