WhatsApp for Samsung Galaxy C7 Pro

This is usually Android's battery optimization or Do Not Disturb silently throttling WhatsApp in the background. Go to Settings > Apps > WhatsApp > Battery and set it to Unrestricted, then open Settings > Apps > WhatsApp > Notifications and confirm the message notifications and their sound are enabled. Also check Settings > Sounds and vibration > Do Not Disturb to make sure it isn't running on a schedule. If the alert still cuts out, clearing the cache under Settings > Apps > WhatsApp > Storage > Clear cache often restores the tone without touching your chats. See how others solved this on Reddit

Lock screen previews need to be allowed at both the system and app level. Go to Settings > Lock screen > Notifications and make sure notifications are on with content set to Show content, then in Settings > Apps > WhatsApp > Notifications confirm the message notification category is allowed to appear on the lock screen with content shown. If they still hide, set Settings > Apps > WhatsApp > Battery to Unrestricted so the app can wake the device to post them. See how others solved this on Reddit

On the older Android version this phone runs, a failed launch is usually a corrupted cache or an outdated build. First clear the cache via Settings > Apps > WhatsApp > Storage > Clear cache (not Clear data, which would wipe your local chats), then update WhatsApp from the Play Store. If it still won't open, back up your chats in WhatsApp > Settings > Chats > Chat backup, then uninstall and reinstall the latest version. Note that very old Android builds may eventually fall outside WhatsApp's minimum supported version, which can also block startup. See how others solved this on Reddit

This is typically a router-side issue rather than a phone fault, often a bad SIP-ALG or aggressive QoS setting struggling with the call's real-time traffic. Test by switching to mobile data during a call: if it's stable, log into your router's admin page, disable SIP-ALG, ease any QoS rules, and update the router firmware. As a workaround you can turn off Wi-Fi and use mobile data for calls when on that network. See how others solved this on Reddit

Yes. Pick a Wear OS or Samsung Galaxy Watch model and confirm it supports notification replies, then install the watch's companion app from the Play Store and pair it over Bluetooth. In the companion app, grant notification access for WhatsApp so messages mirror to the watch with quick-reply or voice-reply. Make sure WhatsApp notifications are enabled under Settings > Apps > WhatsApp > Notifications first, or nothing will reach the watch. See how others solved this on Reddit