I've been struggling with this issue all night. My old router packed it in today (WBR-2310) so today I got a DIR-825. I used the Wizard to connect it to my first computer & everything worked fine. The only problem is I cannot connect anything else to the router. As soon as I make an ethernet connection into one of the other port my network icon on the computer that was initially connected gets a yellow exclamation triangle in it & the network switched from 'Home Network' to an 'unidentified' network. Once this happens I loose all connectivity - internet no longer works, I cannot connect into the router config page, etc (192.168.0.1). The only way I can get a connection is to unplug the cable from the second port, then reboot my computer.
This has been driving me nuts all night... any suggestions?