@Vishlamba

later edit: I am using POE260S, also max. 30W and my eap775-wall work fine. But is meant for 2.5G compared with yours.
For the mobile app, I don't think for now, has 1:1 functions same as browser.

  @liviu2004 HI

You missed this part 

Please note that this is separate from the 6GHz functionality issue. I have another EAP775 connected to a 60W PoE injector. where I was testing 6hgz band. 

The issue is not 6ghz not wokring the issue is, is SG2428P providing power as required, and why there is an error message coming in the app. 

Regarding the 6ghz issue Tplink team has already replied to my ticket informing me issue regarding 6ghz not work, beocuse India just lifed the ban from 6ghz band and it been slowly rolled out. So on that its going to be a wait and what situation for me now.

Are you also from india and testing 6GHZ in india ?

  @Vishlamba My testing was done in The Netherlands. Indeed, rollout varies per countries regulations, and TP-Link must observe this aspect carefully. Thanks for the update, definitely helpful for other readers as well.