For whatever reason fog needs to be connected to the internet or you will get that error. since I have sonicwall doing dchp it doesn’t support option 66 with IP address only hostname.
Since I had to image using fog dhcp I removed the PC and server from the reset of the network… It didn’t like that.
Once it began copying the image I connected it back to the rest of the network with internet access and it didn’t have issues anymore.