Linksys PLSK400 Powerline 4-Port Wired Network Expansion Kit

 Wired Powerline 4-Port Kit

Turn your home's existing wiring into a digital network – instantly
Data rates up to 200Mbps
Compatible with other HomePlug devices
Includes 1 single-port adapter and 1 four-port adapter to connect multiple devices at once.

Just plug the master into the wall socket near your modem and connect the supplied ethernet cable, then plug the slave into a wall socket on the the same circuit in another part of the house, and connect up to 4 devices via ethernet cable.

See the specs on the Linksys site here:

http://www.linksys.com/za/p/P-PLSK400/