Hiya pal
To set the port manually for VNC
1. Open CP
2. Goto "Windows Firewall"
3. Click "Advanced Settings"
4. Click "Inbound Rules"
5. Click "New Rule"
6. Select "Port" click "Next"
7. Select "TCP" enter 5900 in the Specific local ports section click "next"
8. Select "Allow this connection" click next
9. Choose the appropriate options under "Domain" "Private" & "Public" click next
10. Give the rule a name eg. VNC out click "Finish"
Repeat the above for "Outbound" aswell and give that another name