I like to try the PROT P version.
I have an onther job sending files which also fails (not all the time though) to the same ftp server.
The ftp server is filezilla 0.9.29b
In this task I'm uploading a whole dir inc subdirs, and this task failes sometimes.
With the external ftp client, every time is a succes.
Uses Visualcron since 2006.