To configure our boards to use DHCP to acquire an IP address we change the value EnableDHCP inside the registry under HKLM\Comm\ETHNETA1\Parms\TcpIp. Then we simply execute ndisconfig adapter rebind ETHNETA1 which works as expected. If we want to use a static address we simply set EnableDHCP=0 add an additional entry for the static IP and rebind again which works, too.
But after turning DHCP off and on again via the registry the device doesn't get a valid IP address anymore. I already checked with wireshark and can see that the device ist not sending a DHCP request.
With an older image we were able to switch this setting on and off as often as needed and the device always got a valid address when DHCP was enabled.