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: