Hyper-V virtual machine unable to get IP address from DHCP server running on same physical box

I don't think anyone has been answered you yet because it is difficult to truly grasp the meaning of your question.

That said, the best practice on Hyper-V is to reserve one NIC as a "Management Adapter." This NIC will be configured just like any other regular NIC on any other physical host on your network, and you do not use it as a Hyper-V adapter that your VMs or HyperV Virtual Switch will use.

Then use another separate adapter to dedicate to the HyperV Virtual Switch. I would recommend not setting DNS servers or a default gateway on this NIC. This NIC simply needs to provide physical network access to your VMs. Creating an external Virtual Switch is what you want to do if you want your VMs to be able to communicate with the rest of the world.

Then connect your VMs to that virtual switch, give them a full IP stack as if they were regular physical hosts on your network, and go!

If you want those VMs to host services, you will then need to configure your NAT'ing router to forward ports to those internal VMs.

Alright. The problem is solved.

Here is what I did: I switched off my ESX.

I started it again: DHCP started I tried the PXE install, got the 4011 error. Double-checked if my WDS is running:

WDS failed to start. Why? Because port 67 wass already used.

I opened WDS and then set the "Do not use port 67" option and thats it. Everything worked.

So at the end it was just a simple restart to recognise, that I need to start the DHCP first so it gets assigned the port 67 for sure and that WDS does not care about that.