Nextcloud Talk iOS App error with SSL

Good morning to you all,

We have a nextcloud server configured on an Ubuntu 20.04 Server LTS virtual machine with Apache, php 8.1 and a self-signed SSL certificate, all working correctly both on the web and on the desktop computer applications, as well as on Android apps.
We can access correctly the Nextcloud app on iOS accepting the self-signed certificate. However, we are having problems when accessing the Nextcloud Talk and Nextcloud Deck apps from iOS where it shows the following error message:


(the English translation of the error is: Nextcloud server not found. An SSL error has occurred and a secure connection to the server cannot be established. Please check that you have entered the correct Nextcloud server address.)
We understand that it is not a problem of the platform configuration if it allows access by the different means except specifically in this case.
I hope you can help me, thank you very much!

Hey, talk-ios requires that the SSL connection is ATS compliant (see Cocoa Keys for details). If this is not the case, no connection is possible. (The files iOS app does not have this requirement, so that’s why it is probably working there).