Hello!
Do you have Secure Boot enabled?
I worked with this Dell Machine about 6 months ago and don’t have it with me now.
So here it goes.
Ensure secure boot is disabled. You will need to re-enable it for Windows 11 to work., You need to ensure your SATA mode setting is set to “AHCI”. - If you have “RAID” selected (which was the default from the Dell Machines I tried) it will not work. If you have legacy IPv4 PXE booting that would work best, newer computers no longer have a legacy PXE boot, but use UFEI IPv4 PXE booting. Check if that is enabled.Otherwise, check what bzImage files you are using. The bzImage files have the linux kernel drivers which I think I used the latest stable ones I could find. These are placed in /var./www/html/fog/service/ipxe
There are 4 files in there which need to be there
bzImage
bzImage32
init.zx
init_32.zx
Or others depending on what CPU architecture your machines use. These are available on the following URL
https://github.com/FOGProject/fos/releases
I found that some work better than others as the FOG project is maintaining their FOS releases and adding computers. It is possible that one you are using simply does not have the drivers for the PC you are using. I would back up these files before updating these to ensure your older machines can PXE when updating your FOS (fog OS).
Matt