I've spent hours attempting this via the if-up.d method as described in: Question 258580

The script just won't trigger and I realized that this method is outdated because Ubuntu no longer uses etc/network/interfaces - since v. 17.10 we are using Netplan.

Then I spent a couple more hours researching and trying the 'systemd service' method as described in:Question 1184648 which appears to be the more modern method, but my service fails during execution and I don't know why.

I don't know where to go from here. It would sure be nice if my ProtonVPN could connect automatically whenever I have a network connection. Please advise, sympathize, or anesthetize.