I have a fresh installed Nextcloud Box on a Ubuntu Core.
I installed on my iPad and iPhone the app client to sync pics but unfortunately it does not work. It connects and opens the file structure but when I try to upload any file, I get a message that the server is not available. Although I can acess via Browser without a problem.
I found this forum: Download/Upload files fail . Sounds like my problem. But the real issue was solve as a bug in the client code.