Unable to send file to external FTP server from our network

We are not able to transfer more than 20 kb file from WinSCP from our network to an external FTP server via the application script. However the manual transfer of file is working fine. It creates a 0 kb file on external server and when it tries to transfer data the connection gets reset. In the log we are seeing error "Network error: Software caused connection abort". Also we tried to send file with log level - Debug 2. There we saw one more error "Handling network close event on socket 948 with error 10053" and after this we saw previous error "Network error: Software caused connection abort" in same log. We checked with our network team, there is no issue at our network side. We are facing this problem from 4 months now. Can someone help us with this issue.

Please attach session log files for successful manual transfer and failed scripted transfer.

I am sending scripted failure log, and scripted success log. The success log is 4 months old when we didn't had the issue. The manual success log I don't have right now as it was not enabled earlier, will share it once we capture it.

Your server is 10 years old. Did you consider upgrading it?

The source server is Windows Server 2016.

Also wanted to update, from last 2 weeks the manual transfer is also failing intermittently with same error. Sometimes transfer with automatic settings work, sometimes transfer with binary settings work.

Abhinav.hzb wrote:

The source server is Windows Server 2016.

I mean the "server" in the context of your question. So the FTP server.

The destination server is vendor side server. Upgrading them is not in our hands. Also they informed that they are able to receive files from other companies without any problems.

That's not really relevant. Anyway, can you upload the file using WinSCP GUI or using any other FTP client?

Also does the connection always broke after WinSCP sends SSH_FXP_SETSTAT? Try using -nopreservetime to avoid sending that request.