Dear @Spryde, 

Sorry for the delayed response. It takes some time to confirm the information with the R&D team.

Spryde wrote

Did a Wireshark on one of my SSIDs where U-APSD is activated (it's activated with all SSIDs) and also Wireshark says, that 'not implemented'.

See screenshot.

So what does it mean? Does U-APSD really doesn't work at all... Is the Controller setting broken, or am I wrong?

Would be nice to get a feedback. 

To confirm whether the U-APSD is enabled on the EAP or not, we can tell by the VALUE of the U-APSD Field in the QoS Info Field of the WMM Information Element in the beacon. As the image below shown, the value of U-APSD is 1, which means the U-APSD is enabled.

The Power Save state on the Omada Controller refers to whether the connected client is in power saving mode, when the client enters the power saving mode, it is enabled, and when the client wakes up from the power saving mode, it is disabled.

Edit: The Power Save state is not static.

During a connection, the client will set the network card to power saving mode multiple times to save power, so the client may repeatedly enter the Power Save state for a short period of time. Besides, the power save state on the controller doesn't reflect the current state of the client since the info is not refreshed for real-time.