Connect to GMX Calendar (CalDAV), Contacts (CardDAV), and Files (WebDAV). I had to use: 1) https://caldav.gmx.com which becomes: https://caldav.gmx.com/begenda/dav/MY-UNIQUE-ID 2) https://carddav.gmx.com DOES NOT WORK (although the begenda may work but needs unique id 3) https://webdav.mc.gmx.net SEEMS applicable but I cannot get it to work