App stops working randomly
After some time the app stops working and I have to press the start button again.
Huawei Mediapad M3 - Android 6.0
Fixed for me by disabling enery optimization for the app.
I think the app is going into standby mode in marshmallow 6.0 OS. Here is an indepth article about that, Doze, and where and what settings to adjust. Let us know if that works, and make sure you have the setting in the Block This app set to restart on boot as well.
Also, when you find battery optimization settings page, be sure to set "VPN Dialogues" to "not optimized" as well as the Block This app.