Wifi problem on CM12.1

My wifi doesn't automatically connect when a known wifi is in range unless and until I turn the screen on. Means when it's sleeping, it won't connect to any known wifi. If its already connected to a wifi network and if the screen is turned off after that, it stays connected. But lets say power goes off and wifi disconnects because of turning off of the router. When power comes back, and router is automatically switched on, the phone doesnt reconnect automatically when in standby. It connects immediately as soon as I switch on the display. Wifi scanning, keep wifi on during sleep and all those options are enabled. But it still doesnt automatically connect to any known wifi when in standby...I have to turn on the display for that.

Any solutions?