WhatsApp for Samsung Galaxy Pop SHV-E220

Samsung's aggressive battery management is usually the culprit, since it puts WhatsApp to sleep in the background and breaks messaging and notifications. Go to Settings > Apps > WhatsApp > Battery and set it to Unrestricted, then open Settings > Battery and device care > Battery > Background usage limits and make sure WhatsApp is removed from both the Sleeping and Deep sleeping app lists. Keep the app updated through the Play Store, as outdated builds often misbehave on older Galaxy hardware. See how others solved this on Reddit

The heads-up popup is controlled per-channel in Android, so a banner can be off even when sound still plays. Open Settings > Apps > WhatsApp > Notifications, tap the Messages category, and set its Importance to Urgent (make sound and pop up on screen). Then go back to Settings > Apps > WhatsApp > Notifications and confirm the master toggle and the Messages category are both switched on, since either being off will suppress the banner. See how others solved this on Reddit

Delayed notifications that only sync when you open WhatsApp are a classic sign of the phone killing its background connection. Set Settings > Apps > WhatsApp > Battery to Unrestricted, and turn off Adaptive Battery under Settings > Battery and device care > Battery > More battery settings. Also avoid putting the phone into Power saving mode, which restricts background data and is a common cause of WhatsApp messages not arriving until you reopen the app. See how others solved this on Reddit

Recent WhatsApp versions moved popup control to Android's system notification channels, so the in-app Notifications screen no longer forces the banner by itself. Go to Settings > Apps > WhatsApp > Notifications, open each category (Messages, Group notifications, Calls) and set the Importance to Urgent so each one shows as an on-screen banner. If it still fails, clear WhatsApp's cache under Settings > Apps > WhatsApp > Storage and reboot so the new channel settings take effect. See how others solved this on Reddit

Intermittent notification failures usually trace back to a Do Not Disturb schedule, a stale app state, or background restrictions silently re-enabling. Check Settings > Notifications > Do not disturb to confirm WhatsApp isn't muted on a schedule, then force stop and reopen WhatsApp via Settings > Apps > WhatsApp > Force stop. If the problem persists, remove WhatsApp from the Sleeping apps list under Settings > Battery and device care > Battery > Background usage limits and update to the latest Play Store version, which fixes known notification bugs. See how others solved this on Reddit