Hi, samuel
Good day!
Thank you for posting to Microsoft Community. We are happy to assist you.
According to your description, the issue of your concern that you've got an issue when configuring the AIP scanner through the on-prem environment.
For the given issue is relates to Microsoft Azure Information Protection Scanner. Since AIP is out of my knowledge and experience.
Thus, I'm afraid that I could not give you an appropriate suggestion here.
Nevertheless, we would like to refer you into the right place -Microsoft Azure Information Protection which there's a technical support team who dedicating into Microsoft Azure Information Protection Scanner with rich experience and more resources.
We believe Microsoft AIP technical support team will conduct in-depth of this issue and provide you a more professional suggestion.
Thanks for your precious time and your cooperation would be highly appreciated.
Have a nice day,
Microsoft Community Moderator.