A Hyper-V Generation 2 VM is similar to a workstation running UEFI workstation and as such cannot communicate with legacy PXE, but with UEFI boot images.
A VM configured with UEFI will use bootx64wdsmgfw.efi on the WDS server when starting the boot process while a legacy boot will use bootx64wdsnbp.com.
If your network is configured to deploy boot images using legacy methods, this will require you to configure the hardware of the virtual machine. See the link for how this is done. https://techdirectarchive.com/2020/01/19/how-to-setup-a-vm-via-pxe-boot-on-a-generation-1-vm-hyper-v/