Hello,I have a problem with wifi connexion.Data it's transfered only if I have very good signal(all 4 lines up),if the signal drops a bit to 3 lines or less,wifi speed drops to almost 0 mb/s.This happends to any router I connect my phone to.Please advise me what can I do to restore the wifi functionality.I have tried all the methods with no improvements,tried with kit kat,lolipop.

Thank you!