ASP.NET - Website Not accessing for Some Countries

Hi All,

The Website developed using ASP.NET framework 3.5 and deployed in IIS7 windows server 2008. It is intranet application who are all in the office network can access the website.

But I have a problem only some countries(Russia, Germany mainly European countries) are not able to acess the website. I do not know what needs to be checked in Server.

Please Advise.... Thanks in Advance.

Might be some problem with the Firewall