How to manage VLANs on FortiGate Firewall

To create a VLAN on a FortiGate Firewall, head to Network -> Interfaces

Select "Create New" and "Interface"

Give the VLAN a name, and assign it to a physical interface

Set the VLAN ID

Set the IP/Netmask of the VLAN as the FortiGate will serve as the router for this VLAN

Enable "DHCP Server" in order to run DHCP on the VLAN

Set Address range, Netmask (For LAN networks, this is usually 255.255.255.0)

Leave the rest of the options as default, unless required to change

Ensure the status of this interface is set to enabled and select "OK" to apply and save