[Q] Wifi not working. Not a noob topic

Hi,

FIrstly I'd like to say I'm not noob. So please dont treat me like one and tell me to search the forum. I've already did it many times.
Secondly, I've tried MANY Roms. Like a lot. But all I want is something very stable. So I decided to use Stock.

I've tried these ROMs and some more I cant remember:
CM11
CM12
Honami
DextroDroid (wifi worked very well here.. just hated the nav bar and icon size. Coudn't live with it hahaha)
Clean 'n' Tweaked
Matrix
LiquidSmooth
Carbon
PAC-Man
And ALL Stock versions

Sometimes the wifi works after I reflash stock. But then I decide to do something else and the phone gets int oa bootloop and I have to reflash. Then the wifi is messed up again =(
Now I'm testing Kernels.
ThunderZap 4.1 and Extended Stock v6 are the best bets.

I would like to know if you guys have been through this too.
How to make the wifi work again and avoid bootloops?

I'm almost buying a new phone. I'm spending too many hours trying to fix Xperia L.