I am baffled..
ADSL Router = 192.168.1.1
Server (NIC1) = 192.168.1.5, gateway 192.168.1.1
We have RDP connection to windows server forwarded by the ADSL router to the correct machine, all working properly. Because of other routing issues on the server (NIC 2) I remove the gateway on server (NIC1).
Now RDP can no-longer connect to the server, nothing else has changed and if I put the gateway back in it all works fine again.
Firewall is turned off so not causing any problem.