How to disable traffic other than OpenVPN (Android 5.1.1)?

Question

Android

Actually, subject. There is a Samsung A5 (2016). It is necessary to make sure that Internet access is ONLY through OpenVPN (installed and configured). How can this be done? If without root - generally gorgeous. If with a root - remind how it is done now, what are the pros / cons. Thanks in advance for tips.
UPD: Solution found .

Answer 1

So after 4.4.2 there are no more problems, at least in the official client . Yes, and in 4.1-4.4.2 it was treated with the "Seamless Tunnel" option. Root is not needed. But for greater security, note that the connection would not break when the screen is turned off.
The only drawback is that it cannot be configured manually, you need to write a *.ovpn file, put the keys next to the file.

Answer 2

You remove everything from autoload except openvpn and make auto-connection at background start.