Actually that worked because I made a mistake and used the iOS app on macOS m1.
The iOS app works fine though the macOS (m1) still sends :

Error. Please check that URL, username, password, etc. are correct and that the sync target is accessible. The reported error was:

request to http://XXX.XXX.XXX.XXX:22300/api/sessions failed, reason: connect EBADF 10.5.23.85:22300 (Code EBADF)