Forget Your Android Wi-Fi Network And Reconnect

1. Swipe down from the top of your screen and tap the Gear icon to get into your settings.
2. Tap Network settings or Connections 
3. Tap Wi-Fi to get into your Wi-Fi settings.
4. Tap the gear next to the network you are currently connected to and then tap Forget to erase your settings for the network. Your phone will disconnect and will not attempt to reconnect automatically.
5. Make sure Wi-Fi is still turned on. Tap the network name in the list again and enter your sign-in information to connect again.

Why this works:

If you’re having trouble connecting to the Internet, forgetting your current Wi-Fi network and connecting again can help. Forgetting a wireless network erases the sign-in information that you’re using for that network and will prevent the device from trying to reconnect to it automatically. When you choose to connect again, you can enter your sign-in information again and your connection may work better than before.