UEFI PXE Boot stopped working
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Last week pxe booting on uefi suddenly stopped working. BIOS/Legacy pxe still works. Wireshark shows us the communication with the windows dhcp server and the 3rd party network boot server.
DHCP Discover from client, containing a parameter request list
DHCP Offer from dhcp server containing an ip address
DHCP Offer from network boot server containing the tftp server ipBut the client newer responds with a request as it should, instead it seems to discard the dhcp offers and resends the discover until timeout. Comparing this communication to when a bios pxe successfully boots shows that the offer packets are identical.
It is irritating because there were no changes to any system when this stopped working, and the setup is very basic (one subnet, no broadcast blocking anywhere). It's the same client hardware as before (some dell desktops and lenovo notebooks).Any tipps or ideas would be greatly appreciated
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I do not use PXE boot anywhere, so no idea.
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MS can role out BIOS/UEFI updates now. You sure you didn't get an update on those devices?
How about just resetting those UEFI to factory and trying again (making sure PXE boot is enabled after factory resetting).
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I think MTU settings can mess with PXE/TFTP.
Anyway, nothing changes by itself and goes from working to non-working without reason. Just got to find what it is that has changed by logical troubleshooting and elimination.
I would start with wireshark on a port mirror to see the traffic the actual client is seeing. I don't know enough about PXE to be of any help however.
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If it works on Legacy it should work on UEFI. What is the BIOS Setting for PXE on UEFI?
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@Dashrender said in UEFI PXE Boot stopped working:
MS can role out BIOS/UEFI updates now. You sure you didn't get an update on those devices?
How about just resetting those UEFI to factory and trying again (making sure PXE boot is enabled after factory resetting).
We ruled that out because it happens on a multitude of different systems (different hardware), some haven't seen a network or booted windows for months.
@Pete-S said in UEFI PXE Boot stopped working:
I think MTU settings can mess with PXE/TFTP.
Anyway, nothing changes by itself and goes from working to non-working without reason. Just got to find what it is that has changed by logical troubleshooting and elimination.
I would start with wireshark on a port mirror to see the traffic the actual client is seeing. I don't know enough about PXE to be of any help however.
That's what's baffling, we know there had to be some kind of a change but there's only 2 of us managing anything IT related. Wireshark only shows that the packages are in fact being sent but don't arrive at the client or the client ignores them
@dbeato said in UEFI PXE Boot stopped working:
If it works on Legacy it should work on UEFI. What is the BIOS Setting for PXE on UEFI?
It should but it doesn't, we dont' understand it either. The BIOS is set to use UEFI and to allow pxe boot, uefi network stack is enabled.
We currently suspect some switches to not properly forward the dhcp packages but there seems to be no logic behind this because we definetly didn't change anything on them.
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We may be one step closer, but it still does not make a lot of sense. With one specific switch model in between, uefi pxe works. Other switch models (also netgear) it does not. I've changed every single option on the working switch trying to "break" it to find out what option might be the issue on other switches in our network, but whatever options I've set uefi pxe boot kept working.
Here is a graphic to show what exactly I mean.
https://ibb.co/ZWLHpwb
How can it be that it does not work directly on the floor switch, but it does on a switch behind the floor switch?
Again, any hints are greatly appreciated -
@FakeNoMore whenever multiple switches are involved regardless of the problem I start looking at spanning tree protocol issues
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Do you have anything that's automatically setting the VLAN for the port?
