One port of LAGG stops working after FreeNAS reboot


I’m currently using an Intel X520DA2 with a Unifi XG 16. I’ve managed to get LAGG working on LACP. However, if for some reason I have to reboot the FreeNAS, one of the ports stops working (usually the second one). I would have to delete the LAGG, reboot FreeNAS, then make the LAGG again for it to work back to normal. Is there a reason this happens? Anybody else experiencing this on their LAGG setup.

I would check the switch configuration/logs.

Some switches will put a port channel into a fallback mode when they stop receiving LACPDUs which shuts down all but one port in the channel. This behavior prevents loops but allows a server to PXE boot. Since the X520 card can bring its links up before the OS boots, that would trigger the fallback. And on occasion I’ve seen switches get stuck in the fallback state.