Can't connect to internet because of VPN switch to connect automatically( can't cancel、always fail)

Can't connect to the internet because of VPN switch to connect automatically( can't cancel、always fail).

Once iPad connect to any wi-fi, and then if there are any data transfer between the internet and local, you can see VPN(on Setting page) switch off and on very frequently automatically with network broke.

I can't fix this problem with reboot my iPad.

I even can't upgrade to 11.2 because of the network can't reach because of this bug.

You can see Video on here: https://youtu.be/QvqsDdK5-3M

My iPad profile:

iPad Air2(MH182ZP/A)

OS Version: 11.1.1(15B150)