Most cases come down to a single setting
Missing a call or an important message is stressful, but a large share of notification problems trace back to a single permission or a battery-saving feature. Working through the checklist in order usually turns up the cause quickly.
If the notification sound itself is silent
If notifications are appearing but making no sound, check your media and ringtone/notification volume separately, since some devices split these into independent sliders. It is also worth confirming that your connected output device, such as Bluetooth earbuds, hasn't taken over your audio.
Frequently Asked Questions
Notifications only fail for one specific app.
Check that app's individual notification permission and its battery optimization exception separately β this is the most reliable way to fix an app-specific issue.
Notifications arrive late when the screen is off.
A battery-saving feature is likely restricting that app's background activity. Adding the app to the battery optimization exclusion list usually improves this.