Normally this is firewall problem if you can access iis localy. It means the computer you are trying to access:
--> go to that computer
--> open a browser and type: http://localhost/
-->if you can access the iis locally that means iis is running.
-->open the firewall
-->click the - allow a program or feature..
-->find the allow the program called: World wide web services(http)
-->click ok and exit firewall