Hi PatR-31C, we had a similar issue in our production enviroment with 2 ms350 in stack. Those switch are configured with L3 and have uplink to a MX84 After upgrading we experienced a 60% packet loss toward Uplink (internet) connectivity. No problem in L3 Lan routing. We haven't tested your solution yet (about removing channel aggregations), but we would like to know if this is a meraki certified solution or not. Thanks in advance.   ... View more