You may receive the following error when using RDP to connect to a server:
An authentication error has occurred.
The function requested is not supported.
This could be due to CredSSP encryption oracle remediation.
This is due to an MS update repairing a vulnerability.
Execute gpedit.msc and browse to Computer Configuration / Administrative Templates / System / Credentials Delegation in the left pane.
Change the “Encryption Oracle Remediation” policy to Enabled, and “Protection Level” to Vulnerable
Close gpedit and try again!