Is it better to leave Wi-Fi on or off? Some homes don’t have any wireless devices, and a wireless signal in these cases serves no purpose. Another reason to disable Wi-Fi is when the network has a slow Wi-Fi connection. When Wi-Fi is slow, turn off the Wi-Fi on your tablet or phone and use your mobile carrier’s network for faster speeds.
Why does my phone use data when I’m not using it? If the phone is in standby and not connected to power, it will switch to cellular data. Even so, that seems excessive. WiFi assist will use cellular data if the WiFi connection is exceptionally poor or not working for some reason. If you go to Settings>Cellular, you can see what’s using your cellular data.
Is Wi-Fi radiation harmful to humans? There are no health risks from exposure to radiofrequency EMF from Wi-Fi devices in your home, in schools or other areas accessible to the public.
What happens if I keep my mobile data and Wi-Fi both on at a time? Android actually does support simultaneous connection for both 3G and WiFi devices, through an amazing app called SuperSpeed. On LTE phones it will dramatically increase connect speeds.As others have said, when both WiFi and 3G are simultaneously connected, only WiFi will work.