Ethernet splitter vs switch: What's the difference and how do you use them?

Before we talk about the differences between Ethernet splitters and switches, we first need to examine what's inside a typical Ethernet cable. Modern Ethernet cables, specifically Cat5e or better, use four twisted pairs of copper wires, which translates to eight individual copper wires. These days, most devices are capable of gigabit speeds and use all four twisted pairs to send and receive data.

However, not every Ethernet standard requires the use of all four pairs. Older Ethernet standards are limited to 10Mbps and 100Mbps transmission, and these only require two twisted pairs to reach maximum throughput. This leaves the other two pairs in the Ethernet cable unused. And this is where the most basic type of Ethernet splitters come into play. They split the cable's four twisted pairs into two separate two-pair connections. Each connection gets its own RJ45 port, allowing you to connect two different devices.

Passive Ethernet splitters (pictured above) have two major drawbacks, with the most obvious one being that they can only carry 10/100Mbps Ethernet connections. However, the other big catch is that you actually need two splitters for this setup to work. You cannot simply plug one cable from your router's LAN port into a passive splitter and connect two devices at the other end.

This is because passive splitters simply rearrange the wiring so that each device gets two twisted pairs. The router, meanwhile, cannot communicate with two different Ethernet devices through a single physical RJ45 port.