DHCP timeout on reboot

[FreeMinded]

Hi Sebastian

I'm back from holiday and on this issue again...

(2016-02-29 15:04)SebastianRoth Wrote:  Actually looks like it's sending out DHCP request but not being able to properly receive the answers! Consistent to what we saw in this picture you posted: http://ibin.co/2YAgkDQqr9hG (notice ifstat RX:0). Do you actually see the DHCP discovery packets arriving at your DHCP server (wireshark) and being answered? I'd guess so but please make sure.

Here is what happens on cold boot (see http://pastebin.com/6NfVqbtX for detailed Wireshark output)
From iPXE
DHCP Discover
DHCP Offer
DHCP Request
DHCP ACK
And then from Windows
DHCP Request
DHCP ACK

On a reboot the following happens (see http://pastebin.com/Mnm9RkrL for detailed Wireshark output)
From iPXE
DHCP Discover
DHCP Offer
DHCP Discover
DHCP Offer
DHCP Discover
DHCP Offer
And then from Windows
DHCP Request
DHCP ACK

So to me it looks that iPXE is not acting on the DHCP offers on reboots.
Any idea what could be the cause of this?

Side note, the iPXE script is configured to boot from local disc if it's unable to contact our boot control server. Grub get's loaded again and boots into Windows. This is the reason that we have in both cases a successful DHCP request from Windows.