I switched over to chat because the Q&A turn around was faster.
The first issue was the OP had dhcp option 60 defined. This caused the pxe booting client to think the fog server was a proxydhcp server. When the fog server failed to respond the client just gave up. It ignored the dhcp option 66 and 67 settings that were defined.
When the OP removed dhcp option 60 then a new issue popped up with some incorrect policy settings in his windows 2012 dhcp server. After that was fixed and he rebooted the fog server everything started working!!
I’m solving this thread since its now working.