Dear all,
I have opensese tumbleweed and upgraded from 11.03 to 12.0.0
Unfortunately I cannot say if it worked with 11.03 and iphone due to I had none at this time.
When I updated by repository my daughter got her iphone back and then I discovered it cannot connect to port 443 and wants to connect to port 80. Port 80 is closed at my server and I will not open it.
With android it works perfectly. 
Greets
I think iOS tries by default to connect via port 80 first and also tries to get all the .well-known/* service discovery urls (https://docs.nextcloud.com/server/12/admin_manual/issues/general_troubleshooting.html#service-discovery-label). With that I managed to set up calendars and stuff reliably on iOS devices in the past (didn’t check on NC 12).
So, I’m not sure if it works with https only, it probably should. If you specify port 443 and iOS tries to connect via port 80, I don’t see how Nextcloud should fix this.
When you’re using OS X and iOS you have to write in the server case https://mycloud.mydomain.com
If you have a working nextcloud with ./well-known working it won’t block.
I’m using every day calendar with NC 12 and OS X and iOS.
If you don’t have ./well-known working you have to write a longer url for server i think this is that :
https://mycloud.mydomain.com/remote.php/dav/principals/users/myuser/
Hi Nemskiller,
thanks for the hint.
I have no idea what I did different but it works now.
Maybe the “7” was missing at account infos end. 
For me it’s solved now.