@smcadm Seems like google is your friend here - see this:
Updating the Bios firmware has done the trick and PXE boot is working now…
I really don’t understand what’s wrong with HP notebook’s firmware?! We’ve see the weirdest things happening (fatally wrong initialized registers would cause the linux kernel to freeze when booting on the HP x2 210 devices - they send us a patched firmware more than a year ago but have not released a patched firmware officially yet…). So to make a long story short, I really wouldn’t wonder if PXE booting is going to work for you after firmware upgrade.