@helloworld1 I think I have found the issue myself - it is the AP firmware. Once I received my new EAP245, I upgrade to the latest firmware (V3 2.20.0 Build 2020423) immediately without noticing it...

I have a Raspberry Pi 2B with no use and decided to follow the instruction found on other forum to setup Omada SDN Controller Linux 3.2.10. Everything work well except failed to retrieve clients...