Network error: Software caused connection abort when downloading files of a few MB via script

We're running into an issue when getting files of a few MB via a WinSCP script. It works fine when getting the files through the UI.
I've add a timeout of 300 seconds and set the option 'Optimize connection buffer size'

WinSCP version: 5.13.2 (Build 8455)
Windows O/S: (OS 6.1.7601 Service Pack 1 - Windows 7 Professional)

The failure is
> 2018-07-10 11:58:42.953 Type: SSH_FXP_READ, Size: 29, Number: 2309
. 2018-07-10 11:59:06.806 Network error: Software caused connection abort
. 2018-07-10 11:59:06.806 Connection was lost, asking what to do.
. 2018-07-10 11:59:06.821 Asking user:
. 2018-07-10 11:59:06.821 Network error: Software caused connection abort ()
< 2018-07-10 11:59:06.821 Script: Network error: Software caused connection abort
< 2018-07-10 11:59:13.061 Script: Searching for host...[/size]

The full log file and download script files are attached.

Thanks!

Can you also provide us with a log file from GUI showing a successful download of the same files?

I set the debug level to 2, which created a very large debug log file, so shortened it a bit to be able to upload it. Hopefully it contains all the info you need. Thanks!

Sorry for late answer. I was away.

In GUI you are using a binary mode. In scripting, you are using an ascii mode. Does it make any difference, if you switch to the binary mode in scripting?

Ah, thank you. that seems to do the trick. Interesting, because the files are actually ascii and not binary files. Thank you very much.

One quick follow up question:
There are still a lot of instances where the network connection appears to drop, but it automatically reconnects. Is there something we can do about this or should we not be concerned?
I attached an updated log that shows the error
Network error: Software caused connection abort ()
Script: Network error: Software caused connection abort
Script: Searching for host...

Thanks again!

It's definitely not common behavior. But I cannot tell why it is happening. There something wrong about the server for sure, if it crashes with ascii transfers.