WIFI problem, it turns on and it wouldn't connect to my home wifi or any other wifi, and sometimes it connects to the wifi but there's no internet connection although there's internet on my other connected devices to the same wifi, also sometimes when I'm having the problem when I enter wifi settings the phone bugs and says wifi app doesn't respond; Smart doctor says that WIFI is good.

EDIT: I have G6 H870DS Indian model and I recently installed an update, but at the same time I downgraded it to android Nougat and still the problem persists.