First, if you are not running on a current stable firmware release (or better), upgrade to that.
One of the most common causes I run into is with Windows hosts trying to place the WiFi NIC into power-saving mode. Try running this command to disable power saving for WiFi:
powercfg /SETDCVALUEINDEX SCHEME_CURRENT 19cbb8fa-5279-450e-9fac-8a3d5fedd0c1 12bbebe6-58d6-4636-95bb-3217ef867c1a 0
powercfg /SETACVALUEINDEX SCHEME_CURRENT 19cbb8fa-5279-450e-9fac-8a3d5fedd0c1 12bbebe6-58d6-4636-95bb-3217ef867c1a 0
It is common to have to update the WiFi drivers on machines to resolve bugs (I have had a lot of issues with Intel WiFi NICs in particular). Note you may have to go to the WiFi NIC manufacturer to get the latest driver if your machine manufacturer does not supply it.
The above log shows the client has requested disassociation, but we don't understand why. Do you only have Mearki APs, or is this a mixed vendor solution, and something could be sending confusing signals?
I see you have 2.4Ghz enabled. Can you disable this? It only makes life more complicated.
Does Meraki Wireless Health have anything interesting to report?
If you are using WPA2-Enterprise mode and Microsoft NPS, have you got "Enable Fast Reconnect"/"Fast Roaming" on both NPS and the client side?
I can't see any evidence in the log, but client load balancing can cause an issue like this. You could try disabling this on the Meraki side:
https://documentation.meraki.com/MR/Other_Topics/Client_Balancing