Router Or Modem Settings - No Computer On Network Can Reach Server

We have a Comcast business class cable modem with a static IP address. There are two devices hardwired to it; a server and a Linksys WRT610N, The server is hardwired to it with port forwarding set for ports 21, 80 and 5900. It works perfectly and can be reached as intended by the outside world but not by our own network. Our Linksys WRT610N is hardwired to the modem. All computers on the wireless network see each other and can access the internet perfectly. So all seems well enough. BUT, no computer on our network can reach our server. Using the domain name or VNC connections from inside our system results in time outs and no connection.