I've got a Windows desktop workstation that sometimes refuses Remote Desktop Connection. (The client reports that it's not enabled or not turned on.)
Most of the debugging suggestions for RDC and RDP are of very little value: I don't have authentication failure reported, folder sharing works correctly at all times, I can RDC all the other workstations and servers on site at the time the connection fails, the situation comes good next time I check, and there isn't anyone on site at the time the connection fails
One thing I have thought of is that Windows workstation only allows one connected RDC. If for some reason it is failing to drop a connection, it won't be able to permit another remote desktop connection. But that's only a theory: maybe one of the routers is refusing "just this connection" for some unknown reason (there is no other firewall in the route, just the default at the client and server workstations).
What logging can I do at the remote workstation? I don't particularly want to leave WireShark running for 12 hours on the chance of catching something odd, and I wouldn't know what to look for if trawling through 12 hours of network capture for missing transactions ... So I'm hoping to start with something I can enable at the target workstation that will log RDP connections, or, even better, RDC failures. Even absence of RDC failures when expected would be an indication of an odd path failure.