Heimdall

I've just had this exact problem (although with a Dell E7250). Are you happy that the drivers imported without error? I had to apply a hotfix to my 2008 R2 based server: (https://support.microsoft.com/en-us/kb/2837108 found via https://support.microsoft.com/en-us/kb/3025419). After this, e1d64x64.inf imported correctly and the computer picked up an IP address in WinPE as expected.