How to resolve the issue “Remote Desktop Disconnected” or “Unable to Connect to Remote Desktop (Terminal Server)”

NOTE: This is an old post. To learn about RDS in Windows Server 2016, please visit our documentation page   One of the recurring issues seen in product support is why a client cannot connect. Specifically, errors such as “Unable to RDP,”  “Remote Desktop Disconnected,” or “Unable to Connect to Remote Desktop (Terminal server)”  are…