I ran into this problem earlier this week when our remote sites called in stating they couldn’t connect. We are running some windows server 2012 servers and we have published remote apps as well as full-blown remote sessions for our remote locations and mobile users. This affected windows 7, 8, and 10 clients.
When trying to connect to a windows server 2012 via RDP we received this error message:
An Authentication error has occurred.
The function requested is not supported.
This could be due to CredSSP encryption oracle remediation