The last couple of days I have been trying to get the Dell Optiplex 7050m to work with PXE but I haven't succeeded. The strange thing is that using a bootable USB stick made from the bootcd works fine.

What I have tried:

Booting from USB with drivers from the bootcd March driver update 2018 works (haven't tried the August 2018 update yet).
Booting PXE with the August driver update 2018 does not work (Error: Can not find the repository).
Inserting newid="0x8086 0x15e3,e1000e" (found by booting the USB drive in Manual mode and using the command hwinfo --netcard) in z_maintx64.cfg stops the boot process of PXE when trying to load the driver e1000e.

I am baffled by this. Can someone help me with this?

Thanks in advance.