This is an update to my original post about setting up managed switches over a wireless P2P bridge found here. We noticed that the necessary commands changed starting in the FortiOS 7.2 firmware branch. So the new commands are below.
Upstream Switch
This is the switch that is already managed by the FortiGate.
config switch physical-port
edit "port#"
set fortilink-p2p enable
set lldp-profile "default-auto-isl"
set speed auto
next
end
Remote Switch
This is the one on the other side of the P2P bridge you are trying to manage
config switch physical-port
edit "port#"
set fortilink-p2p enable
set lldp-profile "default-auto-isl"
set speed auto
next
end
config switch auto-network
set mgmt-vlan 4094
set status enable
end
config system interface
edit "internal"
set mode dhcp
next
end