Thanks for the data, as you can see in the captures, as soon as the firewall sends a request for the connection, the server is sending a Reset for it, so I woudl suggest you to troubleshoot why the server is sending a reset. Ceck if any firewall on the server is blocking the connection. Try putting an exception for the port 80.
S -------> SYN (initial connection request)
R -------> Reset
Hope this helps.
I think I've fixed it!
The captures were returning with it all clear, so I did some digging and it looks like there was an entry in the registry for the old ip address that stopped IIS from returning any sites.
(HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP\Pa rameters\ListenOnlyList in case anyone else has the problem.)
Once again, much appreciated!