The first way to resolve the 'Function Requested is not Supported' error in RDP, is to turn off the Network Level Authentication on the RDP Server's side. Disable Network Level Authentication on RDP Server. How to FIX: 'The Function Requested is not Supported' in Windows Remote Desktop Connection. The Function Requested is not Supported' in Remote Desktop Connection on Windows 10/8/7 OS. This tutorial contains instructions to resolve the error 'An authentication error has occurred. At the same time, the Remote Desktop connection is successful from Windows 10 based PCs. The Function Requested is not Supported.'. 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.
