To debug the vSZ live the debug logs can be downloaded from Diagnostics>>Application Logs.
There are many services involved, if you are aware of these services and what they do then you can proceed to download these logs.
To troubleshoot any system related issues, event logs are the starting point which would narrow down your search and then checking the following process System, Core, Communicator and Configurer would help in giving more information.
To troubleshoot any authentication issue that in radius authentication or HS then RadiusProxy, SubscriberPortal, and SubscriberManagement are the process that I would look into which would give more information, additionally I would increase the debug levels to find the RCA.
To debug AP issues and client connectivity issues, Events under Access Points are the place to start with then AP Support info, which can be downloaded can give you more insights.
SSH into AP and run "get syslog log" to get live logs.
If you ever run into any issues on vSZ/AP please download AP support info snapshot logs with issue symptoms with time of occurrence and frequency.