Assuming it's not a hardware issue with your phone or your WiFi, make sure you clean flash and don't install any gapps larger than mini (nano recommended).
Had the same issue and when I clean flashed with nano gapps the issue was gone, so I guess try that xD
Thankyou, I'm pretty sure it's not hardware issue because I can connect to other Wifi except one in my house
So yeah maybe I will clean flash