cpyne,
You'd probably have more luck putting this question to the TCP/IP forum, but I'll attempt it anyway.
Are you using DHCP on your PC? Is the router providing the address to your computer?
If the router has an IP address that does not fall within your other computers' netmask, then you won't be able to "see" it.
I would say that you just want to reset it to factory config, but you have to be able to connect to in order to do that (really bad design). And the cable that they use for the console port is custom, so good luck there unless you are handy with building your own cables.
When you post this to the TCP/IP forum, make sure that you include your PC's ip range and netmask, and the ip and netmask of the router (if known).
Did this ever work on your network? Or did you pick this up second hand?
pansophic