ipxe does not accept offered ip?

[Elleni]

I have installed fog server, which works fine as it has been tested with different pcs, among them 1 very old laptop and 1 very actual, newly bought laptops which boot fine via pxe. The new laptop is a HP Probook with the same style white background HP bios as the problematic PC below.

I disabled uefi boot and setup legacy pxe boot.

On our new pcs (HP Elitedesk 705 G5) though, dhcp of ipxe times out. In dhcp server I just see a series of dhcpdiscover and dhcpoffer entries, without an dhcpack in the ipxe phase.

On this pctype where it does not work, I installed an additional nic to rule out a problem of the onboard nic, but it behaves the same.

How can this be fixed? The ipxe version is 1.20.1+.

What information may I provide to find a solution?