I was using the app called VPN 1-Click for a long time. Recently I got root and granted it permissions when it asked for it. I recently removed the permissions from the app because the servers weren't so stable.
Now my phone won't connect the Internet at all. Neither wifi nor mobile data works.
Naturally, the app makes changes in your network configuration.
The problem occurs when you do not disconnect using the exit button within the app. So it seems as if the internet doesn't work is because the server is down. You forget that the VPN is still connected although you think it isn't.
The problem occurs only with root permissions because without root, you can see running VPN services in the notification bar since it's running under Samsung's scope, reminding you that VPN is connected. When using it with root, you just don't see the notification, giving you the wrong idea that there's no working VPN although there is.
Anyways, restarting the phone reverts the configuration to a default state, thus solving the problem.
I don't believe that the app is malware or stealing ID in any way.