While setting up a new Fortigate 30D for a client, I wanted to add a new VLAN for the guest Wi-Fi network. Usually, you just go into Network - Interfaces and add a new Interface there.
On the 30D however, this option wasn’t there. After changing the device from switch mode to interface mode and back, I figured you can’t do it in the GUI. The only way to do it on a 30D is by using the CLI.
To add a new VLAN, go to the dashboard, open up the CLI and enter these commands:
config system interface
set type vlan
set vlanid 100
set interface vlan
set ip 172.16.100.1/24
After running these commands, you’ll also see the VLAN show up in the Network - Interfaces page.