PRTg - no, I don't use this.
For OIDs, please look into the document "Ruckus WirelessTM ZoneFlexTM Access Point SNMP Reference Guide" and a MIB (you have to ask the support for it?)
https://support.ruckuswireless.com/do...
From the guide:
ruckusWLANStatsNumSta OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Number of associated stations."
::= { ruckusWLANStatsEntry 3 }
regards.