I'll continue searching but now with proper tools.
For more advanced users maybe this or this will help - Especially this part of article: "Here is an example script of modem initialization:(...)"
@bigb The script from the gabsoftware link works great when run straight in the terminal, but when put in startup, the vpn tries to reconnect but can't for some reason.
(I also used the same folder, you used in your post but I don't know if this has any influence, just made it easier for me to check the fields and make the new input.)
Any directory should be fine, I've just used the same as on my pc to make checking easier 😉