I have an ASP.net application running on a Windows 2003 + IIS 6 server in the UK accessed from UK and European offices. Some users are getting intermittent "Page cannot be displayed". This might not happen at all for half an hour of continuous use - or it might happen every other click.
- Users on the same LAN as the server never have problems.
- Users who connect over the internet using a VPN client never have problems.
- Users in remote offices connected via a private network get the problem. The office is connected to the data-center via two routers on each end of a private line. We have approached the provider of the private line and they say it's not their problem.
What might be causing this? If it's the private network then how do we prove it? Are there any configuration changes that I can make on the server to make the application more resillient?
If security is a possible cause then I'll go into more detail but it doesn't look like it to me.