Why does Redmorph, sometimes, turns off the VPN and displays the message - " Redmorph Firewall was turned off by an external unknown source"?

Android only permits one app to have VPN control which our app requires. You can toggle this VPN control on/off inside our app using the Firewall toggle switch.  

This message is displayed when the user turns off this permission or when another app with the VPN permission turns on the internal VPN.

In the latter case the Android OS automatically then switches off our control and gives it to the new app.

When we detect that we no longer have the VPN control, we notify you that RM protection has been turned off, and to turn in on.