Video: WiFi disconnects automatically on android device
In case if the WiFi of your android device keeps on disconnecting automatically, the first thing is you need to make sure that the WiFi signal is strong so that your android device is always connected to the WiFi. If the signal of the WiFi goes down then your phone will be disconnected automatically. The next thing you need to check is there are certain applications which can disconnect your WiFi. So, go ahead and open "Settings". Go to "Connections". Select "WiFi" and tap on this more option here. Advanced and there is an option here "WiFi control history" under "Network settings". Select it. Now these are the two applications that can turn on the WiFi automatically. So, what you do is, make sure either to select it and Force stop or uninstall those applications.
Also if after installing some applications your WiFi started to disconnect automatically then make sure to delete these applications and check if the android device will work fine..