Just to be absolutely sure, i moved my Nextcloud docker into the same user defined Network, and configured NC to use the local alias for the LDAP docker: Works perfectly.
Its just Zammad that says that it cannot connect to the LDAP server, but is also quite vague about whats the problem. i mean it should be either / or “Can’t connect to ‘ldap_ldap_1’ on port ‘389’, Can’t bind to ‘ldap_ldap_1’, 49, Invalid Credentials” either it cant connect or it has incorrect credentials.