S4 - 3G - WIFI won't turn on - Plz Help

Hello all,

Like thousands of S4 owners my wifi also doesn't work. But my problem is a little strange.

My wifi when I enable it, it says 'Turning On' and stays there for about three minutes and returns to off again.

But sometimes it just works.. it connects and internet is full speed and all is well.. then suddenly after sometime it stops again.

I am in this dilemma since over two months now and I don't know what to do.

Because it works some time I suspect it could be a battery issue, the wifi demands certain current from the battery and when the battery is not able to provide it the wifi won't start ( I have tried with the charger plugged in also, it behaves the same, wifi wont work ), although I am no expert in this.

What I have tried so far,

Tried installing 5.1.1 rom,
Tried installing stock ROM,
Tried various times to rename wpa_suplicant file
Tried without SIM and without SDCARD
Tried with a different battery
Opened the phone and re plug that blue wire
Tried 4.4.2 stock ROM

etc etc

No use, I have to depend on phones mercy till I get WIFI and data packages are very expensive here :(

Please advice something else I can try

Thanks.