This might help. Saw on a new machine the other day in the BIOS when I enabled the network boot in integrated peripherals another option appeared to specify TCP/IP V4 IPV6 and TFTP. Never seen the option before. Worth checking. In your WDS setup you have configured the DHCP requirement so PXE boot can find a DHCP server to get an IP to contact WDS and load the boot.wim file? This file is then sent using TFTP (Trivial File Transport Protocol) to the client. Vlans these can cause all sorts of problems?
