In v5 firmware you can automatically suppress APs that are detected as “on-wire”. This means that the Fortigate detects a wireless BSSID whose value is adjacent to a MAC ID detected on the wired network.
The following needs to be configure at CLI:
config wireless-controller setting
set ap-scan enable
set on-wire-scan enable
set ap-auto-suppress enable
end
One of the radios in the AP should be set to monitor and auto suppression also needs to be configured in the AP profile:
config wireless-controller wtp-profile
edit 221B
config radio-1
set mode monitor
set rogue-scan enable
set ap-auto-suppress enable
end
end
Rogue APs that are detected on-wire should now be suppressed, note that they will not be shown as suppressed in the GUI:

Verify the AP will suppress by connecting to the AP and run the following command:
cw_diag -c ap-suppress
Suppressed AP list:
bssid
08:5b:0e:0b:2a:23
00:1b:11:cc:80:4a <--- this one is the D-Link as seen above