@Abutaleb75 

my message is not quite on the point of your post, but I'll write it anyway

my opinion: you didn't quite choose the right devices for such a relatively large-scale task

you should have looked at tp link omada business solutions

https://www.tp-link.com/en/omada-sdn/

directly on your problem, most likely there is a maximum number of access points in some models

I ran deco with a maximum of 9 S4 points, apparently 10 points is the limit 

  @David-TP 

Hi David,

I'm using 1x TL-SG1428PE and 3x TL-SG1218MPE switches.

And yes, all Decos are working fine and LED is green as it should be. It's only the App showing all Satellite offline.

App log submitted a minute ago.

Highly appreciated,,,