Tomcat 6 browser from some proxies are unable to resolve url

I have configured my server.xml with host name=myweb and hosted it on a server but I am having problems as few of my friends are able to access the site using myweb:8081/App/welcome.jsp but some are unable to do it but I found out that those people are who were unable to do so using the above url are able to access t开发者_如何学Gohe site using the complete server url such as gvad.sc.pe:8081/App/welcome.jsp

Any Ideas that I can solve it?