I have in the past used Autowikibrowser on the private wiki ccmdb.kuality.ca which we host on Dreamhost using a LetsEncrypt certificate.

When I went back now to use it I get two errors when trying to set the site using HTTPS:
First:
Title: Error connecting to wiki
Msg: Authentication failed because the remote party has closed the transport stream.
Then when I click OK:
Title: Netowrk access error
Msg: The underlying connection was closed: An unexpected error occurred on a send.

If I try to set the site using HTTP I get a much longer error:
Title: Error connecting to wiki
Msg: An error occurred while connecting to the server or loading project information fom it. Please make sure that your internet connection works and such combination of project/language exist. Enter the URL in the format "en.wikipedia.org/w/" (including path where indes.php and api.php reside). Error description: Object reference not set to an instance of an object.

I tried a second. low-traffic wiki I run (wiki.squirrelslair.ca), same problem. On that one I changed the hosting domain settings and disabled HTTPS, and then tried to connect with HTTP only. This works just fine, which makes me think that my URL is not the issue, and that fundamentally the internet works between AWB and my site. So something goes wrong when I turn on HTTPS on my site. That gives me a work-around, but not a satisfying one... Is there a bug or what am I doing wrong?