Windows Server 2008 runs in higher security level. By default, Windows Server 2008 does not allow previous versions of Windows computers to access the Server Core via Terminal Services. You must turn off the higher security level to allow them to access via Terminal Services
- Enable the terminal services if it is not enabled already:
Cscript C:\Windows\system32\Scregedit.wsf /ar 0
- Next, run the following command to turn off the higher security level:
Cscript C:\Windows\System32\Scregedit.wsf /cs 0