disconnected due to inactivity after 58 seconds?

[craig_knights_7]

At our school, our users are complaining about trouble staying on the wifi.  Often changing SSIDs or laptop's Wifi off / on will help get them reconnected.  Some background:  vSZ Essentials 3.4.2.0.169  We have 52 R600's, and a flat network topology.  We have up to 1000 users peak.  Half iPads, a quarter Macbooks, the rest Windows or Android.

In the logs I often see entries like this:

2018/03/06 13:30:19
205
Client connection timed out
Informational
Client [dsc] disconnected from WLAN [JMCstaff] on AP [ELC 203@D4:68:4D:22:CB:E0] due to inactivity.

2018/03/06 13:29:21
206
Client authorization successfully
Informational
Client [dsc] of WLAN [JMCstaff] from AP [ELC 203@D4:68:4D:22:CB:E0] was authorized.

The client connects, then gets disconnected due to inactivity 58 seconds later?

More background:
We are doing radius auth on the staff and student SSIDs to a Windows 2016 NPS

More looking at the AP log, there is a client timeout after 8 seconds?

This problem has been happening for months if not years, and had survived across updates to the vSZ, both software and hardware.  The hardware is a modern processor with plenty of RAM running on vmWare on an SSD.

Where to go next?

thanks,
Craig

[pasquale_monard]

are they roaming?
after initial connection is made, do they go to sleep? 
Radius auth? WPA2-enterprise -> Eap-Peap? eap-tls? 

ChannelFly enabled? Background scanning? How aggressive is it?