Make sure that you have layer 3 roaming enabled if each floor the wireless traffic is placed on a different subnet. As gas as disconnections throughout the day, you need to look also at how your SSIDs are configure. Just like with Cisco's enterprise controllers, it's best not to mix WPA and WPA2 encryption methods. Your devices should all support WPA2/AES which is WPA2-Personal or WPA2/-Enterprise if you are using radius. Have you validated that there is more than enough coverage?
Thank you for your answer Scott.
I read that the layer 3 roaming parameter in Meraki is for networks where APs are not in the same subnet.
In my case, all APs are in the same subnet.
Could I make this change or not in my case ?
Well if your SSID's are all mapped to the same vlan, then you don't need to. It's when you have each floor for example on a different vlan for SSID X.
Do you have another ideas ?
Do you know roaming and disconnections issues about two following wifi cards adapter : Intel Centrino Wireless-N 1000 and Intel Centrino Advanced-N 6205 for Meraki solution ?
The only issue can be with driver versions. I know that the 62xx works well with the v15. Look to see if there are updates for the drivers and tests. When you are roaming while walking the floor, what are your ping times when pining the gateway for example? Test with an open ssid also and see if the issue goes away. This would tell me that it's the wireless NIC's that might be he issue then.