The following error appeared on a Windows 7 based computer, when I tried to connect to a Server 2012 via the Remote Desktop Connection app:
“An authentication error has occurred. The Function Requested is not Supported.“. At the same time, the Remote Desktop connection is successful from Windows 10 based PCs.
Method 1. Disable Network Level Authentication on RDP Server.
Method 2. Enable the Encryption Oracle Remediation on RDP Client
In Windows Home versions:
run Command Prompt As Administrator.
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\CredSSP\Parameters" /f /v AllowEncryptionOracle /t REG_DWORD /d 2