Why Wifi turns off when I unlock screen?

[skyrail]

I have a Galaxy S4 still running android kit kat, installed Buzz launcher and DU battery Saver, greenify.
Besides I have an AutomateIt rule which turns wifi on when the screen turns on. It does it. wifi is then on until I swipe screen to unlock it. then wifi abnormally turns off.

Alternatively, if deactivate that rule, and leave wifi on, then turn off screen, wifi turns off after a few seconds.
Wifi turns on only when I unlock screen and not just after the screen turns on.
Such process definitely work but is not an option for me, because I have to enable wifi manually.

Where should I search to solve this issue?

 

[B. Diddy]

DU apps seem to be a bit more problematic than others, based on posts I see on the forums. Try uninstalling it.