I am trying to set up a switch between my PS3 and my PC. I have an external DSL modem. I purchased a 5 port switch(Rosewill RC405-x) but no luck. Can I use an ethernet splitter instead?

Firstly, I presume your router has only one LAN port (that's the port you plug the computer or PS3 into). I also presume you have working ethernet cables.

1 Connect any port on the switch to the LAN port on the router.

2 Connect any port on the switch to the computer and any other port to the PS3.

3 Use both devices at the same time for fun and profit.

If it doesn't work we start trouble shooting. If it works without the switch then there is something wrong at the switch. Look for the link lights at either end of the cables - it should be green at both ends. If you see no light, try another cable. If you see an orange light it (generally) means a bad connection or a slower link - try another cable but don't sweat over it if the device works.

Ethernet spliters are no good and i would not recommend using one because it is like a hub (only have half duplex) technology where as a switch has full duplex which will allow you to communicate between more than one device at the same time. All you should need to do is plug it into a power socket and run the Ethernet cable supplied in the box into a port on the back of your modem, plug your ps3 and computer into the switch via an ether-net cable and all should work fine. You may have to log onto your router because you may need to open a port so that the switch is able to communicate with your router.

You did not explainhaow you connected all your equipment together.
Connect your PC and PS3 into the 5 port switch.
Connect your DSL modem into the 5 port switch, if there is a WAN/internet port on the 5 port switch then connect the DSL model into this port.
You may need to power off the 5 port switch wait a 1 min and power up the 5 port switch again so it can setup an IP address table for the connected ports.
If this still does not work the replace the 5 port switch with a normal 5 port hub.