Actively refused connection on Distribution running on port 80

If you're running Windows Server 2008, be sure to disable IIS, since it acts as a web server and thus by default it intercepts incoming traffic on port 80.

It is recommended that you also switch to a higher port number that won't cause issues if you have the ability to.

Make sure NTL Studio Distribution has administrator privileges. Right-click on the shortcut, select "properties" and then on the Compatibility tab, make sure "Run this program as an administrator" is checked.