Support intro
Sorry to hear you’re facing problems 
help.nextcloud.com is for home/non-enterprise users. If you’re running a business, paid support can be accessed via portal.nextcloud.com where we can ensure your business keeps running smoothly.
In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 20.0.5): 22.2.3
Operating system and version (eg, Ubuntu 20.04): debian 4.19
Apache or nginx version (eg, Apache 2.4.25): Apache/2.4.38
PHP version (eg, 7.4): 7.3.31-1~deb10u1
The issue you are facing:
I do have the waring message about /.well-known/caldav and /.well-known/carddav when I connect thru Firefox, but not with Safari.
I try to connect my iPhone or my Mac but none works.
The output of your Nextcloud log in Admin > Logging:
(too many Exceptions :
RuntimeException: App class OCA\ocDownloader\AppInfo\Application is not setup via query() but directly)
The output of your Apache/nginx/system log in /var/log/____:
0.0.0.0 - ni [23/Dec/2021:17:35:40 +0100] "PROPFIND /remote.php/dav/files/user-xxx/ HTTP/1.1" 207 6264 "-" "Mozilla/5.0 (Macintosh) mirall/3.3.6git (build 7956) (Nextcloud, osx-21.2.0 ClientArchitecture: x86_64 OsArchitecture: x86_64)"