WhatsApp for Samsung Galaxy XCover 3

Most likely yes. The XCover 3 shipped with Android 4.4 KitKat and can be updated to Android 5.1.1 Lollipop at best, which is below WhatsApp's current minimum (Android 5.1 is the borderline cutoff and newer features increasingly require more). Once your device falls under the minimum, WhatsApp stops getting updates and eventually stops connecting. Back up your chats now and plan to move to a newer phone running a current Android version if you rely on WhatsApp daily. See how others solved this on Reddit

In WhatsApp, tap the three-dot menu > Settings > Notifications and make sure Message notifications are on with Popup set to 'Always show popup' and a sound/light selected. Then open the phone's Settings > Apps (or Application manager) > WhatsApp > Notifications and confirm 'Show notifications' is enabled. On the XCover 3 (Android 5.1) also check Settings > Apps > WhatsApp and ensure it isn't restricted, and disable any third-party battery-saver or task-killer app that may be closing WhatsApp in the background. See how others solved this on Reddit

First open Settings > Apps (Application manager) > WhatsApp > Permissions and confirm Storage is allowed, since the XCover 3 often saves media to the microSD card and a blocked permission stops downloads. Then in WhatsApp go to Settings > Storage and data > Media auto-download and enable photos/video for mobile data and Wi-Fi. Finally verify the phone's date and time are correct (Settings > Date and time > Automatic), because a wrong clock breaks WhatsApp's secure connection and blocks media. See how others solved this on Reddit

On the XCover 3, open WhatsApp > Settings > Chats > Chat backup and run a backup to Google Drive (and a local backup to the SD card as a fallback) using the same Google account you'll use on the new phone. When you install WhatsApp on the new Android device and verify the same phone number, it detects the Google Drive backup and offers to restore your chats. Moving to an iPhone instead requires WhatsApp's official Move to iOS / transfer tool, as Google Drive backups don't restore on iPhone. See how others solved this on Reddit

On this older device it's usually a third-party battery/power-saving app or a rugged-phone power-saving mode closing WhatsApp in the background, plus a full cache slowing things down. Make sure WhatsApp is excluded from any battery-saver or task-killer app, keep Settings > Accounts auto-sync on, and clear WhatsApp's cache via Settings > Apps (Application manager) > WhatsApp > Storage > Clear cache (this is safe and won't delete chats). If it still freezes, reinstalling WhatsApp after a Google Drive backup often helps on the aging XCover 3. See how others solved this on Reddit

Open Settings > Apps (Application manager), find the app currently set as the default, tap it and choose 'Clear defaults' to remove the 'Always open with' association so the phone asks you again next time. If you can't find which app it is, use the three-dot menu in Settings > Apps and pick 'Reset app preferences' to clear all default-app choices at once (this won't delete any data). See how others solved this on Reddit