Microsoft Windows Home Server 2011 is a 64-bit operating system. The program requires 64-bit support in the Graphics which the DN2800MT lacks.
Desktop Boards Supported operating systems
Note: DN2800MT is 32-bit only
I'm having the same issue with Windows Server 2008 (x86) so for me it is not a 64 bit issue.
Did you ever get yours working with WHS or did you have to go back to Win 7?