It turns off when no device is connected after some time.

Hello there! Jan here, Samsung moderator. We are very sorry that you experienced this kind of inconvenience. As I can see, you’re having issues in your wifi connectivity, for quick troubleshooting steps you can follow these instructions:

 

You can soft reset your device and try to connect on the router and try to reboot the router as well. Restarting your phone can clear glitches and help it reconnect to Wi-Fi.

 

Also, you can back up your data and do a Factory Data Reset. With this, it will erase everything on the device and will go back to the original factory state. (Settings > General management>Reset>Factory data reset)

 

If the issue persists after factory data reset, it would be better to bring the device to the nearest service center in the area or you can check this link for your reference  https://www.samsung.com/ph/support/service-center/

 

Kindly give us an update here once everything is fixed. Thank you for your continued support on Samsung. Thank you and have a nice day.