Message: [server name] disconnected. Return Code (Disconnect Reason) = 4: An internal error has occurred.
Possible cause: When using RDP through a Cisco ASA (SSL VPN) device, NLA can cause connectivity issues.
Workaround/Solution: Disable NLA in the connection properties in Royal TS under Advanced. You may also need to disable the requirement for NLA on the server you want to connect to (in the System Properties -> Remote).
Message: [server name] disconnected. Return Code (Disconnect Reason) = 50331677
Possible cause: After installing Windows 8.1 update, a connection can fail when an RD gateway server is used and a logon message is configured.
Workaround/Solution: Disable the logon message. More information: http://dave.harris.uno/remote-desktop-gateway-after-windows-8-1-upgrade-no-longer-working/