Just the network settings. I've never networked a PS2, but just basic networking stuff, I know if you have say your WAN IP address entered(so your modem would work) but then switch to a LAN, then it won't work. Either set to DHCP and try to release/renew the address, or just manually enter the address(should be something like 192.168.1.x, subnet: 255.255.255.0, gateway 192.168.1.1(whatever the router's IP is)
lhstud10 - In my experience, the crummy software that comes with routers leads to more problems than anything.