Hi Fahrizal,
Since this is a old version, I'm not sure about the exact path.
However, you can try upgrading to the least standalone version 9.8.1.0.101 from the below link.
https://support.ruckuswireless.com/software?filter=68#firmwaresYou can also try to put 100.0.0.0.127 on the AP, but I do not want the AP to brick.
Try a step by step upgrade from 2.6.x to 9.8.1.0.101 >> 9.8.2.0.15 >> 9.8.3.0.14 >> 100.0.0.0.127 >> 104.0.0.1347
Once on 104 version, you should be able to connect to the vSZ on 5.2 version.