There are indeed splitters that make a single CAT5e outlet in to a double socket. This works by utilising the 2 pairs that aren�t usually used when a single device is connected via Cat5e connection.

(http://www.cablenet.co.uk/catalogue/adaptors.htm) last 2 items

In reply to a post by XRaySpeX:

Puzzled! This seems to be more a software problem than a hardware wiring one.

How will the router know to give them diff. IPs and distinguish between PCs?

The splitter makes it 2 separate wiring connections - so as far as the router is concerned it is no different to having 2 PCs connected. You have a splitter at both ends so you actually use two ports on the router which then combines to a single cable and then splits at the other end back to 2 connections for 2 different devices.

Edited by ian72 (Wed 16-Jun-10 13:22:02)

Either buy a simple 4 port switch, stick an unused router in there or buy a double socket and use one of the other pairs. A switch is the simplest and best solution.

For most home uses Cat5e Networking cable only uses pairs 1,2 and 3,6. This leaves pairs 4,5 and 7,8 redundant. A cat5e splitter takes pairs 4,5 and 7,8 and wires them to pairs 1,2 and 3,6 on a second plug. For this to be of any use you must use a splitter at either end of the cable being split, so you would still need two ports on your router for two devices, but would only need one cable.

Unfortunately doing this increases noise on the cable, reducing signal quality, and so reducing the distance you can get a reliable signal along the cable. Also specialist connections need the extra pairs, like PoE for example. Also Gigabit connections unlike 100Mb and 10Mb connections use all four pairs, and so will fall back to the slower 100Mb speed on a split cable.

As has been suggested already in this thread a more reliable solution would be to use a network switch at the other end of the single cable to your router. This will avoid the problems associated with using a cable splitter.

I saw you post perhaps I'm a little late

Ethernet running up to speeds of 100mbps uses 2 pairs of a 4 pair cable assuming cat 5 or above (pairs 2,3 Orange & green, the splitter takes advantage of this by then using pairs 1 & 4 for a 2nd circuit.

its only when you are using gigabit ethernet where all 4 pairs come into play and gigabit ethernet will run on cat 5e and above.

hope that helps
simon@mrcable