I'm not fluent in SmartZone platform, but we have a KBA-2433: Maximum values for Inactivity time out & Grace period
https://support.ruckuswireless.com/articles/000002433... that suggests you might be able to use "Grace Period" in addition to maximum "Inactivity Timeout"?
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Inactivity timeout can be set on WLAN at ZD web UI >> Configure >> WLANs >>(Edit a WLAN) >> Advanced options
For vSZ/SZ: Navigate to the WLAN> Configure WLAN>> Advance Options.
Inactivity timeout refers to the disconnection of the idle clients from the associated AP.
For ZD,
Minimum Value: 60 Seconds
Maximum Value: 500 minutes
For SZ/vSZ,
Inactivity timer:
Minimum Value: 60 Seconds
Maximum Value: 1000 Seconds
Grace period allows disconnected users a grace period after disconnection,
during which clients will not need to re-authenticate, on Web based authentication
(including Guestpass and Hotspot).
For ZD,
Minimum Value: 1 minute
Maximum Value: 144,000 minutes
For SZ/vSZ,
Minimum Value: 1 Minute
Maximum Value: 14,300 Minutes