I have a server running Windows 2003 that I am not able to make a RDP connection to on a local network. It was multi-homed but for troubleshooting this problem I have disabled all but one NIC. When trying to connect to the server by RDP it gives a generic Protocol Error message and says it is disconnecting and to try connecting again. Actually the connection is never really made.
I did a packet capture of the connection to this server as well as the connection to a server with out this problem. The TCP handshake goes fine in both instances. However on the working server a X.224 connection request is made by the client and confirmed by the server before proceeding with the RDP connection. With the problem server the client make the X.224 connection request but the server never returns a confirmation.
I'm not familiar with X.224 and google doesn't turn up much. The server is definitely listening on port 3389 but I have no idea what would cause the X.224 connection to fail on this one server.
BTW, this server is newly installed in our datacenter and RDP hasn't worked on it from the beginning.