Restart your device
The first and simplest is to restart your device. This step may sound the easiest one, and most of the time this is all that is required. Restarting your Android device usually fixes a bad connection.
Switch between data connections
Users can also switch between Wi-Fi and mobile data to check if the internet is working when it’s connected back to Wi-Fi. You can change the data source through your Android device’s Settings menu.
Select Network & internet or Connections (depending on your device) in the Settings menu and turn off the Wi-Fi and connect your device to mobile data to see if there’s a change. If you can connect to the internet with mobile data, switch back the connectivity source to Wi-FI and check again.
Toggle between enabling and disabling Airplane mode
Another trick that may work is enabling or disabling the device’s Airplane mode through the Settings menu. If restarting your device and switching data connections doesn’t work, try enabling the Airplane mode and wait for 10 seconds before disabling it. Now, check if your connectivity is back. This is another commonly used fix that often revives internet connectivity in Android smartphones.
Restart your wireless router
If all of this fails to work, restart your wireless router. But make sure that you read the router’s manual for instructions before this on how to reset it. While you should follow the steps given in your router’s manual, one thing that works for all models is: After unplugging the router, wait for 30 seconds before you plug it back.
Finally, if none of these steps help you get back your phone’s Wi-Fi connectivity then you should contact your internet service provider.