IIS Server is not responding to computer name:portnumber instead of localhost:portnumber

i have tried to deploys the MVC Application in IIS Server (Windows 7 Ultimate (32 bit)) i have configured my web site in localhost:81 is perfectly working. when i have use my computer name : 81 (Server-PC:81) is showing Service Unavailable HTTP Error 503. I have entered the same url (http://Server-PC:81) in network connected System is showing Web page as not found

Please notify me if i have missed any setting such as firewall etc in my pc or any other step i need to do. thanks in advance.