@treebeard : Thanks for sharing the reason! Hopefully it will help others to prevent this experience.

What does exacly exec do? I ask, because sh doesn't work for my script like . does. I'm also interested as I want to run VPN on boot and keep it always on. Here are my scrips and other information. Also, what are the nmcli commands that enable cellular data? I tried to find it and I'm run out of ideas.