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Error “CredSSP” Error using rdp on Windows Server 2012 R2


You are trying to connect via rdp to windows server 2012 r2 and you receive this error :

An authentication error has occurred.
The function is not supported.
Remote Computer: your hostname
This could be due to CredSSP encryption oracle remediation.


Download and install KB4103725 form Microsoft Update Catalog

After installing you need to restart the server.

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Windows, change rdp port

The rdp defaul port is 3889.

To change this port :


In windows firewall, create a windows inbound rule on this new port on windows firewall.


  1. Start the registry editor. (Type regedit in the Search box.)
  2. Navigate to the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\PortNumber
  3. Click Edit > Modify, and then click Decimal.
  4. Type the new port number, and then click OK.
  5. Close the registry editor, and restart your computer.