I’ve noticed that if WDS is running on any other server, clients will look there first.
I just moved FOG VHD off virtual box and onto HyperV and had problems until I realized that I got a new IP assigned.
This was due to new mac address being issued which made my prior reservation invalid.
In HyperV, VM settings, Advanced Features, I was able to assign a static MAC address to match the prior DHCP reservation