WhatsApp for Samsung Galaxy S5

Eventually, yes. WhatsApp keeps raising its minimum Android version, and the original Galaxy S5 tops out at Android 6.0 Marshmallow, so once the required version moves above that the app will stop getting updates and later stop connecting. The S5 Neo (Android 7.0 Nougat) has a bit more runway but faces the same fate. To stay safe, back up your chats now with Settings > Chats > Chat backup to Google Drive, then restore that backup on a newer phone when the cutoff arrives. See how others solved this on Reddit

Once WhatsApp drops support for your Android version, the Play Store stops offering updates and the app eventually stops connecting, and there's no fix on the device itself short of a higher Android version (which the S5 can't officially go past Marshmallow). Before the cutoff, open WhatsApp and back up your chats with Settings > Chats > Chat backup to Google Drive, then restore them on a newer phone. After that you can repurpose the S5 for offline uses like a music/podcast player or a Wi-Fi security camera. See how others solved this on Reddit

First check WhatsApp's own alerts: open WhatsApp > Settings > Notifications and make sure message and group notifications are on. Then confirm system notifications are allowed under Settings > Applications > Application manager > WhatsApp > Notifications. Most missed-notification cases on Samsung come from power saving killing the app in the background, so turn off Ultra power saving mode and make sure WhatsApp isn't restricted under Settings > Battery (or Settings > Power saving). Finally, check Do Not Disturb is off. See how others solved this on Reddit

Make sure WhatsApp has the permissions it needs: go to Settings > Applications > Application manager > WhatsApp > Permissions and enable Phone and Microphone so calls can ring. Then in WhatsApp open Settings > Notifications and confirm call notifications are on with a ringtone selected. Also turn off any battery/power saving restriction on WhatsApp so incoming calls aren't blocked while the screen is locked. See how others solved this on Reddit

A factory reset wipes WhatsApp's local database, so your best bet is restoring from a backup rather than scanning the phone. Reinstall WhatsApp, verify the same number, and when prompted restore from Google Drive (if you had Settings > Chats > Chat backup enabled). If a local backup survived, the msgstore.db files live in Internal storage/WhatsApp/Databases on the S5, and reinstalling will offer to restore the most recent one. Without any backup, recovery after a reset is generally not possible because the data is overwritten. See how others solved this on Reddit

The Galaxy S5 Neo runs Android 7.0 Nougat, so it can still run WhatsApp for now, but with the support cutoff approaching it's worth backing up chats with Settings > Chats > Chat backup to Google Drive and planning to migrate. In the meantime you can use it as a secondary WhatsApp number on a spare SIM, a media/podcast player, or a dedicated camera. Just watch the minimum Android version WhatsApp requires so you know when it stops connecting. See how others solved this on Reddit