I want to connect to a Team Foundation Server through HTTP. I am not in the network (local nor VPN) with the server I want to connect to. I use the public IP of the server.

From my laptop with XP it can be reached easily - for example when I enter the http://serverIP:9200 in the Internet Explorer, the browser asks me for a password and if I fail to log it shows that the Access is denied.
9200 is a port number.

When I connect a laptop with Vista and do the same, a browser just informs that it cannot display the page. I can't also connect to the server via telnet. The behaviour is the same also when I turn off the firewall on Vista (on XP I do not need to turn off the firewall). What then can be blocking this connection?? Are there any security settings that I should check?

There is no problem to connect to the Web server from the same network as this TFS.

I would be very thankful for some help or suggestions.

Greetings,
Polo