I have a dedicated Windows Server 2008 on which I'm hosting one of my sites. Most of the visitors are able to access the site but some complain that they cannot. Upon digging into the issue, it turns out that when the firewall is disabled, there are no issues at all. But the moment the firewall is turned back on, the same issue surfaces where some of my visitors are unable to access the site (or the server itself - by pinging it or doing a trace route).
Any thoughts how this could be fixed?