Seeking help with the SFTP Functions plugin: I am trying to send a file using th

Seeking help with the SFTP Functions plugin: I am trying to send a file using the "Send File Over FTP" smart node. I have tried many combinations and there is no clue as wht this fails in the application server log.
I have configured the External System Key with username and password (both tested and valid values), set the host name (same as used and test with in filezilla), set the port to 21 and remote path to "/". The document is named as 1-123123.zip.
Despite various tweaks and changes to the settings nothing has helped, most errors returned "illegal filename for a PUT" which seems odd as I can upload the same file with filezilla no problem.
Any suggestions welcome!
Thanks from a frustrated user.

OriginalPostID-221266

OriginalPostID-221266