Networking issues - routers/switches etc

[Joe 90]

Evening.

Right, I'm a student, in halls. Our network is authenticated by MAC address. I currently run my PC and PS3 through a linksys switch.

The authentication on my port is limited to just these 2 (MACs) devices so I thought it'd be perfect to return after christmas with my DD-WRT powered linksys router.

I've changed the settings on my router so that the DNS/Gateway and subnet are those which the PC picks up when i'm connected through the switch. And then also got my router to clone my PC's MAC so that it is then authenticated.

So far so good I thought. after i'd done this the router got an external IP, and it filtered through and gave my PC internet access. Although this only lasted a few moments, then it went back to limited or no connectivity, like before i'd changed the settings.

I then thought powering down might help so turned off the PC, then power cycled the router, booted back up etc. still no joy. I also now can't even connect to my router (very odd, i know)

Just to test things out i booted up the wii and fired up the wireless search - no problems there. It found my router and the live connection, and connected to the web, downloaded a recent update and seemed happy enough. (router has been reset so wireless is unsecure atm)

So, it seems that when cabled up the router connects to the network and gets through to the internet and then is connectable via wireless, but not through the wired connection to the PC.

Anybody got any ideas what might fix, first off the fact that i can't connect to the router when thats plugged in? i can't understand that first off, and then the rest, i guess if the PC connects to it then it should pick up the net (from what happens with the Wii)