We have just receved new computers Dell AIO 7470 and we found that when we send wake up on LAN, approximately 10 hosts from total of 25, block on tftp server and ask to enter it when we boot pxe. Second test different hosts make the same thing. We got the wiresharck file and please somebody to check it. This is a brand new model in our lab. I can show you too the dnsmasq config, just in case me missed something there.
output.pcap
# 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,,192.168.149.43
# 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,,192.168.149.43
dhcp-boot=net:UEFI,ipxe.efi,,192.168.149.43
dhcp-boot=net:UEFI64,ipxe.efi,,192.168.149.43
# 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=192.168.149.43,proxy,255.255.252.0