Sure, The first pic shows my connection to the LDAP server, the second shows the objects for authentication. All of that works fine. The authentication works perfectly and the Mail app in Nextcloud even logs into the server and passes the email through IMAP.
The third pic shows the toggle setting to allow users to change their password. The are allowed to do this on the iRedMail server. In fact for now, the workaround is that I have to send the user to Roundcube to change their password and then that is what they use the next time they use Nextcloud.
The last pic shows the result of trying to change the password inside Nextcloud. The only thing I am unsure of is the popup note on the third pic about passing an encrypted password. I'm not sure if that is happening or how to even view enough log data to see what is taking place between the two servers.
Show us some screenshots of NextCloud related to (LDAP) password change, maybe we can give some hints.