Remote Desktop Authentication Error Has Occurred. The function requested is not supported.

From here: https://social.technet.microsoft.com/Forums/exchange/en-US/46e1cd52-52b3-4427-88a3-200f87319e23/remote-desktop-authentication-error-has-occurred-the-function-requested-is-not-supported?forum=w7itpronetworking 

Here is the FIX for this issue ..

Change the Group Policy on your local client to use the vulnerable setting 

Run:  gpedit.msc

Go to à Computer Configuration -> Administrative Templates -> System -> Credentials Delegation -> Encryption Oracle Remediation

Open - Encryption Oracle Remediation à  choose Enable  à change protection level àVulnerable à Apply