Please try the following steps:
- Check the PlayStation® status page to see if there are any network issues.
- Restart your PlayStation®4 console.
- Perform an internet connection test by selecting Settings > Network > Test Internet Connection.
- If possible, try connecting to the internet using a wired connection.
- Turn off your router, wait at least 5 minutes, then restart it.
- Update your router to the latest firmware. For details, please contact the manufacturer.