Please use my ltsp.conf file here exactly.
# Don't function as a DNS server:
port=0
# Log lots of extra information about DHCP transactions.
log-dhcp
# Set the root directory for files available via FTP.
tftp-root=/tftpboot
# The boot filename, Server name, Server Ip Address
dhcp-boot=undionly.kpxe,,<fog_server_IP>
# Disable re-use of the DHCP servername and filename fields as extra
# option space. That's to avoid confusing some old or broken DHCP clients.
dhcp-no-override
# inspect the vendor class string and match the text to set the tag
dhcp-vendorclass=BIOS,PXEClient:Arch:00000
dhcp-vendorclass=UEFI32,PXEClient:Arch:00006
dhcp-vendorclass=UEFI,PXEClient:Arch:00007
dhcp-vendorclass=UEFI64,PXEClient:Arch:00009
# Set the boot file name based on the matching tag from the vendor class (above)
dhcp-boot=net:UEFI32,i386-efi/ipxe.efi,,<fog_server_IP>
dhcp-boot=net:UEFI,ipxe.efi,,<fog_server_IP>
dhcp-boot=net:UEFI64,ipxe.efi,,<fog_server_IP>
# PXE menu. The first part is the text displayed to the user. The second is the timeout, in seconds.
pxe-prompt="Booting FOG Client", 1
# The known types are x86PC, PC98, IA64_EFI, Alpha, Arc_x86,
# Intel_Lean_Client, IA32_EFI, BC_EFI, Xscale_EFI and X86-64_EFI
# This option is first and will be the default if there is no input from the user.
pxe-service=X86PC, "Boot to FOG", undionly.kpxe
pxe-service=X86-64_EFI, "Boot to FOG UEFI", ipxe.efi
pxe-service=BC_EFI, "Boot to FOG UEFI PXE-BC", ipxe.efi
dhcp-range=<fog_server_ip>,proxy
As long as you have at least dnsmasq 2.76 or newer it will work correctly. Don’t forget to replace <fog_server_ip> with the IP address of your fog server.
ref: https://forums.fogproject.org/topic/8725/compiling-dnsmasq-2-76-if-you-need-uefi-support/5
