Hmm, I don't know. I can't see it from a PC that is also behind the wall. It gets a failure to connect error on IE. I placed the PC in the DMZ and didn't make any difference. But if you say it works, then thats a start 
My router is an integrated router/cable modem/wifi, so I can't place one of the PC's in front of the router.

My router is an integrated router/cable modem/wifi, so I can't place one of the PC's in front of the router.
