Error: Could not write to transfer socket: ECONNABORTED - Connection aborted

Hello –

Since recently participating in new security upgrades required across my organization, I have encountered the following error when attempting to upload large files to my Box account using the Box FTP service (using Filezilla as a client):

:           Error:               Could not write to transfer socket: ECONNABORTED - Connection aborted

The security  upgrades included an Azure Active Directory Join, as well as adoption of Windows Defender as our standard AV software (replacing Symantec). 

Prior to these changes, utilizing the Box FTP service worked reliably for me, with upload of files several GBs in size taking less than 15min. 

Using as a test case a 4.4 GB file I uploaded by FTP prior to the security upgrades, I tried again – both with and without VPN, and with the FileZilla timeout set alternatively to 7,200 sec (2 hours) and to 240 sec.  Though the successful transfer percentage varied in each case, it appeared to be independent of both parameters, and – in any event – in all instances the transfer continues to fail with the above error returned.

Incidentally, I am still able to upload directly to our Box account (via click-and-drag into a browser window) but will need the FTP service going forward as I’m in frequent need of uploading large files. 

Thanks in advance for any ideas !

[personal information--redacted]