Cannot get PXE boot from SCCM
If you’re doing bare metal OS deployment in a typical environment that has multiple VLANs across a single or multiple locations, clients that are not in the same segment as the SCCM PXE Service Point may not be able to boot from the network to the WDS. This is because clients have to be told where is the PXE server is and what file to boot from. To do this, you have to configure Option 66 and Option 67 on your DHCP server scope options where option 66 is your FQDN of your PXE server (e.g. pxe.mycompany.com) and the bootfile (SMSbootx86wdsnbp.com).
After that it works like a charm!