4-way RJ45 splitter divides a single Ethernet port into four output ports, allowing multiple devices to share one network cable, but it functions as a network economizer, not a true network switch. It typically works for Gigabit Ethernet and below, distributing the signal across the cable's pins without adding or processing data. A common use is to connect up to four devices to a single cable run by sending two different signals down one Ethernet cable to two separate splitters at each end.