I've been following the discussion on LACP and STP issues with Meraki devices, particularly since the 15.21.1 and 16.9 updates. It's clear that many users are experiencing similar problems.   As RWelch mentioned, ensure the root bridge priority is correctly configured on the core switches (MS425s) to avoid loop issues.   ... View more

Oh man,.. I've been fighting with LACP since 15.21.1.  Tell me, when your LACP links seem to be working properly, do you randomly have STP take them down?  Also, do you have intermittent traffic issues, some devices seem inaccessible from one device but not another on the same switch, then suddenly the issue resolves itself?   My upgrade today to 16.9 seems to have made LACP worse than 15.21.1 because it used to feel like just Cross Stack LACP was an issue, now LACP between two single switches is also giving me fits.  I've disabled one link in the LACP group for all of our 66 switches for now until I can figure this out.  With the link disabled everything is working perfecty.   James ... View more

Yes, when updating or I think when rebooting the devices to be more specific. But on a daily basis I'm not having any issues, so what you are experiencing is very weird. Have you contacted support? Can you share all settings from the ports on both sides here? Maybe there is something that you are just missing? ... View more

Thanks for the info, we will look into this and try to just upgrade a small network first. Thanks! ... View more