You may have the need to connect your FortiWifi to another access point via wireless bridge. Here’s a little tutorial on getting this set up.
First we need to change the local radio to client mode (Wifi Controller ⟿ Manager Access Points ⟿ Local Wifi Radio):
You’ll now see the Wifi Client config section under the Wifi Controller settings, here’s where you’ll select which SSID you’ll be connecting to:
As this will likely be your main internet connection you’ll want to make sure it’s pulling the default gateway from the DHCP server: