Just download the DNSet from Play Store and check auto star on the app This works for me on my WiFi issues. Now I can connect to and get e-mail and notifications on my phone (LG G3).the only thing that I steal having problems is the battery drain . Hope works for you.
To fix the WiFi problem (no connection, no notifications or slow down) on lg g3 download DNSet app from Play Store. On the app check auto star.This works for me, now my phone WiFi and notifications works better than before. Hope works for you.