Samsung
Turn Wi-Fi On or Off auf Samsung
Wi-Fi on a Samsung phone controls two things at once: local data exchange with nearby devices and, more importantly, your connection to the internet through a router. If the toggle is off, no app can reach the network, even though mobile data might still work as a fallback.
You find the switch under Settings ➔ Connections, where the Wi-Fi toggle sits at the top of the list. Tapping it flips Wi-Fi on or off immediately, no restart required.
Leaving Wi-Fi on all the time can drain the battery slightly faster, since the radio keeps scanning for known networks in the background. Turning it off manually helps when you are far from any trusted network or want to force mobile data for a specific app.
If Wi-Fi is on but you still cannot connect, the issue is usually the router or a saved network profile, not the toggle itself. In that case, check the password or forget the network before you troubleshoot further.
Airplane mode disables Wi-Fi automatically along with mobile data and Bluetooth, so check that mode first if the toggle appears greyed out.