File Upload Performance Issue

Hi Team,

we have an on premise Appian 21.X setup.

For some of our end users, who are external users of the application, are using VPN to access application. They are currently facing issue as below

• the files are dragged on the form (max 2 at a time, avg 5 MB file)
• Form is submitted
• user waits for the upload to happen but it fails to happen or sometimes take time for user to keep waiting for file to show 

While looking at File Upload component documentation, I see below.

Temporary files

• When a file is uploaded, the component updates with a temporary Document representing the uploaded file. Between the upload and the form submission, the file on the server is an inactive temporary file and not accessible except through fv! variables described in the File Name, File Description, and Validations parameters. This is the only way to access file metadata before the form is submitted.
• If a file is uploaded to a form that is never submitted, the temporary file is automatically deleted after 30 days

As I understand, the actual file from user's machine will get uploaded to Appian only on form submission.

We have checked from backend that if the file is uploaded to Appian, then rest of the process (to make entry in tables, launch approvals etc) finishes in 5-10 sec.

So has anyone seen issue with files coming over VPN/remote connections taking long to upload in Appian or timeout? Is there a way this can be improved for the end user.?