@george1421
That was it! The Asus laptop finally got registered with the Fog server!

Thanks a lot for the help!

@george1421
By the way, the laptop in question is an about 3 years old Asus UX302LA
It got secure boot disabled, at least now while testing. Can secure boot be used with PXE?

That did unfortunately not work. I did use your configuration, then simply restart the server before my restart.

port=0
log-dhcp
tftp-root=/tftpboot
dhcp-boot=undionly.kpxe,,192.168.0.2
dhcp-no-override
dhcp-vendorclass=BIOS,PXEClient:Arch:00000
dhcp-vendorclass=UEFI32,PXEClient:Arch:00006
dhcp-vendorclass=UEFI,PXEClient:Arch:00007
dhcp-vendorclass=UEFI64,PXEClient:Arch:00009
dhcp-boot=net:UEFI32,i386-efi/ipxe.efi,,192.168.0.2
dhcp-boot=net:UEFI,ipxe.efi,,192.168.0.2
dhcp-boot=net:UEFI64,ipxe.efi,,192.168.0.2
dhcp-range=192.168.0.2,proxy

#end of /etc/dnsmaskq.d/ltsp.conf

The dnsmasq version I use is the default deb package from Debian (9.1) Stretch:
dnsmasq 2.76-5
dnsmasq-base 2.76-5+b1

I have just reconfigured and rebooted my server, and hopefully this is the reason! I know my system is UEFI, not regular BIOS.

I got a Fog server configured according to the instructions:
https://wiki.fogproject.org/wiki/index.php?title=Using_FOG_with_an_unmodifiable_DHCP_server/_Using_FOG_with_no_DHCP_server

This works with virtual images and computers with regular network cards, however, I got an Asus Ultralight Laptop which have to use a provided USB network adapter. When trying to start this system with PXE boot, it does get its “Station IP” from the DHCP server, but unlike the other machines, no gateway or other IP addresses are listed, it exit and start regular boot from its internal drive.

I am thus assuming it is something wrong with the setup. Configurations:
#/etc/dnsmasq.d/ltsp.conf
port 0
log-dhcp
tftp-root=/tftpboot
dhcp-boot=undionly.kpxe,192.168.0.2
dhcp-no-override
pxe-prompt=“F8 for boot menu”, 3
pxe-service=X86PC, “Boot from network”, undionly # Might machine not identify as X86PC due to USB network card?
dhcp-range=192.168.0.2,proxy
#end of /etc/dnsmaskq.d/ltsp.conf

Any ideas?