Troubleshooting client drops requires looking at logs for an affected client MAC to see why they disconnected...
Where your 10 APs are located relative to clients is also important. Did you do an initial site survey to assure you have required
coverage in all areas? Do clients report drops more in some areas? You might have obstructions or interference affecting client
connectivity. Do your clients roam frequently or work from the same stationary workspace, and do both type users experience probs?
Does everybody have a problem at the same time? These observations can help focus troubleshooting.
The ZD WebUI Administer/Diagnostics page, has a Debug Logs section where you can enter a specific client MAC address, and
check certain components. For client disconnects, I'd use Access Points, and Client Associations. Run with these settings until
your client reports a problem. You click the Save Debug Info button to save your logs, when you get their report.
Go also to the Monitor/Access Points page, and if you know the AP this client was on last, click the little blue/green (System Info) icon
to the far right of that AP. Tech support can analyze your AP support info client details, with the ZD debug log output, to tell who dropped
whom, and for what reasons.
Personally, I recommend update your Apple firmware. Good luck and best regards.