Contacts are synchronized in both directions via CardDav contacts between eM Client, the host IONOS in Germany and a Samsung Android smartphone. DAVx5 is used as the DAV server on the smartphone. If user-defined phone fields are now entered in the smartphone, they appear correctly in eM Client. However, this does not work the other way around. If user-defined fields are created in eM-Client, these are transferred to the smartphone as “other”. What do I need to do to solve the problem with the user-defined fields?