FortiSwitch with Lenovo VLAG

Hello FortiSwitch integrators

Any one managed to make it work a FortiSwitch connected to a pair of VLAGed Lenovos.

• FortiSwitch 124F / 7.2.7 unmanaged
• Lenovo RackSwitch G8124-E / 8.3.5

It was working fine with Cisco but couldn't manage to do it with FortiSwitch.

Configuration was like this (same on both Lenovos)

interface port 1
  switchport mode trunk
  switchport trunk allowed vlan 1,100,200

interface port 1
  lacp mode active
  lacp key 10

vlag enable
  vlag tier-id 5
  vlag adminkey 10 enable

On Cisco was like that:

interface Port-channel1
  switchport trunk allowed vlan 1,100,200
  switchport mode trunk

interface GigabitEthernet0/1
  switchport trunk allowed vlan 1,100,200
  switchport mode trunk
  channel-group 1 mode active

interface GigabitEthernet0/2
  switchport trunk allowed vlan 1,100,200
  switchport mode trunk
  channel-group 1 mode active

On FortiSwitches I created a trunk from 2 ports, LACP active mode, allowed VLAN 1,100,200, but according to my first tests it doesn't work, I mean no traffic seem to pass.

Sadly I had to roll back without being able to collect relevant logs, so actually I'm not sure it didn't work because of VLAG, but can actually be a STP issue or anything else.

Any similar experience or useful hint would be appreciated.