bootp doesn't work with Realtek 8029

[Thilo Rießner]

I am using an embedded PC (AP-486LH) and want it to execute a netboot via 
grub. After typing bootp grub print the following messages:

Found Realtek 8029 at 0xff80, ROM address 0x0
Probing...[NE2000/PCI]

And then hangs. I tried already the complex-rl-2000 fix, but it did not 
help. 
I am using grub version 0.5.95
What could be the possible problems? (BIOS, Bootp,...)
Any help apreciated