WhatsApp for Samsung Galaxy C7

The Galaxy C7 shipped with an older Android version, so newer WhatsApp builds eventually drop support for it and you get stuck in that loop. First try installing the APK directly from whatsapp.com/android (enable 'Install unknown apps' for your browser when prompted), since the Play Store may only offer a build your OS can no longer run. Before doing anything, open WhatsApp > Settings > Chats > Chat backup and save to Google Drive so nothing is lost. If sideloading still fails, the lasting fix is moving your number and that backup to a phone running a newer Android. See how others solved this on Reddit

This is usually a connection or background-data restriction rather than a real outage. Go to Settings > Apps > WhatsApp > Mobile data and Wi-Fi, and make sure 'Allow background data usage' and 'Allow data usage while Data saver is on' are enabled. Then toggle Airplane mode on and off to reset the connection. If it only happens on Wi-Fi, forget the network under Settings > Connections > Wi-Fi and rejoin it, and clear the app cache via Settings > Apps > WhatsApp > Storage > Clear cache. See how others solved this on Reddit

On the C7's One UI this is almost always battery optimization putting WhatsApp to sleep. Go to Settings > Apps > WhatsApp > Battery and set it to 'Unrestricted', then confirm WhatsApp is not listed under Settings > Battery and device care > Battery > Background usage limits > Sleeping apps. After that, re-check Settings > Notifications and, inside WhatsApp > Settings > Notifications, that an actual tone (not 'None') is selected for message and group notifications. See how others solved this on Reddit

The C7 still runs WhatsApp, but as an older device it no longer gets security or OS updates, which is what eventually breaks WhatsApp support and notifications. To stretch its life, keep a few GB of storage free (Settings > Battery and device care > Storage), clear WhatsApp media you don't need, and back up chats regularly to Google Drive via WhatsApp > Settings > Chats > Chat backup. Once WhatsApp starts refusing to update, that's the signal the device has aged out and it's time to migrate your number to a newer phone. See how others solved this on Reddit

Yes, as long as the watch is paired and has notification access. Pair it through the Galaxy Wearable or Wear OS companion app, then grant notification access (Settings > Apps > 3-dot menu > Special access > Notification access, or via the watch's companion app) so WhatsApp alerts mirror to your wrist. Whether you get full quick-reply or voice-reply depends on your watch model and on the WhatsApp version your aging C7 can still run, so test with one chat first. See how others solved this on Reddit