TFTP issues with current build

[NiKiZe]

your best friend is probably tcpdump or wireshark so that you can see what is going on, and compare non working with working

also worth mentioning wimboot, and suggesting that you skip tftp, WDS isn't exactly the fastest thing (much due to TFTP)

Windows TFTP is much of a black box, I think there is a few howtos on ipxe.org, might be worth reading, not as howtos in your case but mostly about all the gotchas with windows tftp server.