Woops EDIT.
My DHCP server IP is different from my router too.
During the install when you are prompted with -
Would you like to setup a router address for the DHCP Server? [Y/n]
Choose: Y and enter the IP Address of your router.
and
Would you like to use the FOG Server for DHCP Service? [y/N]
Choose: N
You can edit the fog settings after the install. They are located in /fog/.fogsettings
In a way, Fog doesn’t really need to know where you DHCP server is but the DHCP server needs to know where FOG is located. Scope options 66 and 67
The .fogsettings doesn’t contain any info about your DHCP serveralt text