My router (Billion 7800DXL) died a few days ago so I've bought an Airport Extreme to replace it. Everything works fine except Microsoft Remote Desktop. I cannot connect to my Windows PC through my iMac or MacBook Pro. I've added Windows Remote Desktop to network settings in Airport Utility so port 3389 should be open and I'm not using any software firewalls either on the iMac or the PC. When trying to connect I get the message "Unable to connect to remote PC. Please provide the fully-qualified name or the IP address of the remote PC, and then try again." I've changed nothing except the router. Any ideas, please?