PXE boot error

[NiKiZe]

I'm expecting that you are seeing Network unreachable (http://ipxe.org/28086011) from ifstat?

The first error you gave is after iPXE exits?

we also know that you are using undionly
We do however not know if you are using an embeded script? if so post it (my guess is that it is missing a dhcp line)
Or are you configuring everything manually from embedded script?

If not embedded - I would expect totally different errors, such as no configuration method which would due to "dhcp issues" with much more explanations and suggestions on the error page.
A good place to start for the general iPXE boot concept is http://ipxe.org/howto/chainloading
I'm not saying that the page has a direct solution to your problem, but give the full page a read if you haven't already