Network connection lost

use WinSCP Version 5.9.2
we have SSIS packager to send a file to vendor using WinSCP SFTP protocol. Error shows up "Network connection is lost" when the job is in middle of sending a file. please find the attached session log. please advise.

Please read documentation:
https://winscp.net/eng/docs/message_software_caused_connection_abort

If that does not help, come back.