Fortinet FortiGate 1U Quick Start Manual page 168

Configuring the internal
wired network to use DHCP
Edit the internal interface.
Set Addressing mode to Manual and
enable DHCP server. Take note of the IP
range.
Go to Firewall Objects > Address >
Addresses.
Set Type to IP Range and set Subnet/IP
Range to use the IP range from the DHCP
server.
148 The FortiGate Cookbook 5.0.