As mentioned, try a reboot of your router. Possibly even a reset, but make sure you have all your settings backed up first, or at least written down somewhere. Another possibility is the Wi-Fi channel you're using. I use a free app called Wi-Fi Analyzer and I have switched channels a couple of times to one that is not as crowded by other routers in the area. Remember though that if you change the channel you're using on the router to change it on any devices where it can be manually set...such as a laptop or tablet. The phone itself doesn't have the option to choose the channel. It will just connect on whichever one is set on the router. Also, use 2.4Ghz instead of 5Ghz as it helps with battery drain...at least until "they" fix lolli-****.