What would normally be a very simple remote desktop error to troubleshoot is muddied a bit by Centrify, who brokers the connection to the target servers. Someone was trying to connect and got this fun error:

Failed to login to the target system. Reason: RDP Error (0x2000D) [ERRCONNECT_CONNECT_TRANSPORT_FAILED]: The connection
transport layer failed..

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Transport-layer issues might have you looking at cipher suites and stuff, but this user was able to connect to other servers fine, so permissions seemed like the most likely thing. And that's indeed all it was, he wasn't in a Windows security group with permissions to connect to the server. Normally you'd get a clean "Access Denied" message from Windows but, since Centrify is in the middle, it didn't do a great job relaying that message back to us.