Ok so I'm new to this and decided hey lets have a go.

I got it all working great and then all of a sudden after a server reboot I got this:

PXE-E51: No DHCP or Proxy DHCP offers were received

My DHCP,DNS,AD and WDS are all on the same box, I spent hours trawling the net and didn't find the answer to my problem but have stumbled across it although about 10hours wasted for a really simple solution

The cause: seems my WDS side is loading before my DHCP is having chance to establish hense WDS can not talk to DHCP to get the pxe connection going.

What did I find:

If i close the GUI for WDS and open the GUI for DHCP, find my server int he tree and right click then select restart.  wait for this to complete (that's the important part)

Once the above is done open my GUI for WDS and again find the relevant point in the tree, right click and restart

Low and behold my connected laptop is now able to connect to the WDS.

I posted this in hope that it will save someone else a heck of a lot of time (can't promise your issue is the same as mine as there are so many different possibilities.)