We have been experiencing a similar issue with firmware versions above 25 with MR42, MR53, and MR55s.  Our wireless networks are segmented by site so we rolled back two sites to firmware 25.13 that don't have MR55s (which require firmware 26+) and have seen the connection drops stop and overall connectivity stabilize.  Our networks on firmware 26.6 with MR55s and/or MR42s/MR53s continue to have dropped connections.  We have a case open with Meraki support as well and have been trying to capture the air when the drops happen per the request but have not been able to because of the intermittent nature of the drops.  Havee you found a resolution?   ... View more