This is the default behaviour when your device is in "Do not disturb" mode. If this is not what you need, you must adjust your "Do not disturb" settings.

Your device can be in "Do not disturb" mode either because you manually set it up, or because you are in a period where you have configure your device to go to "Do not disturb" mode automatically.

Please check in iOS control panel that "Do not disturb" mode is not active:

You can also see that you are in "Do not disturb" mode, thanks to the little moon in the top bar:

To check the "Do not disturb" schedule:

  • Open iOS Preferences:

  • Open to "Do not disturb" option:

  • Make sure your settings are matching your schedule requirements: