Connecting NC15 Calendar to OS X

It seemed to me, that I have a simmalary problem to

I tried, what is shown there as a solution - but I still am not able to connect.

I set up NC 15 on a testserver, using only a local IP and NO SSL,
So the OS X URL should be

I split the URL into and /nextcloud/remote.php/dav/principals/users/USERNAME/ using Port 80.

At the apache log, I get - - [10/Mar/2019:10:35:42 +0100] “PROPFIND /nextcloud/remote.php/dav/principals/users/USERNAME HTTP/1.1” 401 557 “-” “Mac+OS+X/1
0.13.6 (17G5019) CalendarAgent/399.2.2”

and nothing else.
I don’t have problems connecting to the calender by Browser.
And I can access the calender using the Outlook-Sync-Tool and sync it with my Outlook 2007 using Windows 7.

But I fail using OSX or IOS…

Apple dropped cal-/carddav sync support for plain http.
So you have to configure your server to serve Nextcloud via https and not via http to make the synchronization work with your OS X/iOS devices (you might then have to delete the accounts from the devices and readd them).
A selfsigned certificate is good enough.

found that info in the meantime in a different forum.
Now I try to get my testserver running https/ssl.

At Firefox it works after adding den Exeption for the selfsingned cert - but
It seems, that OSX does not like selfsigned certificates…
I found no place to accept it.

On the iphone, it works…