Yes this can be a problem if your SonicWall doesn’t support dynamic boot options. The quickest and most direct route is to install dnsmasq on your FOG server to supply only the pxe boot information. Your sonicwall will supply all other dhcp settings except pxe booting.
If your pxe booting computers are on a different subnet than your fog server, you will need to update your dhc-relay/dhcp-helper service on your subnet router. Add the fog server as the last dhcp server in the helper service. Then everything will just work. If everyone is on the same subnet then just install dnsmasq and it will work.
@kamil .fogsettings file is hidden. In linux when a file name begins with dot ( . ) then file is hidden.
Question on bitlocker. Yes and no will this be a problem. No it will not be a problem in that FOG will backup the protected images in RAW disk mode.
Yes it will be a problem because fog will not be able to resize the disk because the partitions are protected with bitlocker. Also if you move the image to a different computer, that bitlocker protected disk will not boot because the values stored in the TPM chip will be different on a different computer.
So while you can copy a bitlocker protected disk you can not move the image to a second computer and think that it will work.