I'd be very interested in hearing what connection type you've set up in FileZilla if it works there. If you set up the same connection type in jAlbum then it should really work as well in jAlbum as in FileZilla. If not, let me know!
I do not know if gepeto will answer you but as I am also at the host 1and1 IONOS I had the same problem but easy to solve. On the French forum I already replied to this member but apparently he did not understand.
For security reasons the host has changed the server names. Before they were of the form ftp.domainname.com and are now of the form homexxxxxxxxx.1and1-data.host
where the x's are a series of numbers.
And the protocol went from ftp to sftp
Filezilla always works with old coordinates not the jAlbum ftp that only works with the new coordinates.