What to Do If VPN Keeps Disconnecting

On Android the usual cause is battery optimisation: the system suspends the app and the tunnel drops. The app offers to lift that restriction — accept it, or allow unrestricted background activity for RaccoonLine in your system settings.

The other cause is the node you were routed through going offline, which is normal in a user-powered network. Reconnect or use Random. The app can tell a dropped tunnel from a dropped internet connection and will not tear down the session when the network itself disappears.