Hello,
I have been looking for a solution to this problem for few hours without finding any interesting post.
I found that the PXEserver.exe was listening to port 4011 on the address 127.0.0.1 only. I reinstall the PXE server (file PXE.exe) and during the install I selected the IP address of the NIC on wich I want to install PXE.
I hope that helps.
Cheers
Laurent