Tunnel server URL: Secure Connection Failed


(Couldn’t find a category for tunnel, I hope this is OK to ask here)

I’ve just started using the tunnel.exe app to create a connection to my XAMPP server here, using the resulting URLs to connect from the web, e.g. https://myGreatURL.zoe.labstack.me
Now, when I try to connect, I get the Secure Connection Failed error:
The connection to the server was reset while the page was loading.
When I simply go to https://labstack.me/, I get the same error.

I tried using regular HTTP instead of HTTPS, but it always redirects to HTTPS.

Now, pardon my inattention, I don’t know if the domain itself has always been showing that message; maybe it was never meant to be used directly?
It might be possible I mangled some of my server settings while working locally, not noticing changes in its online behavior.

But in case it is an undesired behavior of the labstack.me server: Any ETA on when that might be fixed?