Samsung
Turn Mobile Data On or Off auf Samsung
Mobile data controls whether your Samsung phone uses your carrier network for internet access when WiFi is unavailable. Disabling it stops all cellular data traffic, including app updates, messaging, and browsing, while calls and texts keep working normally.
You find the switch under Tap on Settings ➔ Tap on Connections ➔ Tap on Data usage ➔ Enable or disable Mobile data. This is the same toggle you can also reach from the quick panel by long-pressing the Mobile data tile.
On dual SIM devices, this setting only applies to the SIM card currently set as your default for mobile data. If you use two SIMs and internet suddenly stops working, check which SIM is set as the data line before assuming the toggle failed.
Turning mobile data off is useful for avoiding charges while roaming or staying within a limited plan. If your goal is only to save data rather than block it completely, using Data saver mode is often the better fix since it keeps mobile data active but restricts background usage per app.