iPXE detecting NICs from USB, but not from HDD

[Solo0815]

Debug-Mode doesn't give us anything new, same result. No NIC detected, net0 doesn't show up in ipxe and NO debug messages.
ifstat and dhcp doesn't give any output.
From "config" i get also no net0 device, but if i scroll down, there is a entry with: errno: 0x2e022001
Whatever this means.

And yes: I can boot over PXE with hitting F8 at the right time and all works. But I wanted to be able to boot from ipxe IN the grub2-menu.
My PXE-server isn't running all the time, so chainloading is no option ...
the same ipxe.lkrn/iso works on my laptop and in VirtualBox.

I think linux16 is the right way to boot the ipxe-kernel, because Ubuntu does it the same way, also it is described here: http://hmontoliu.blogspot.de/2010/12/gpx...grub2.html
What can I do to let ipxe recognize my NIC?