User gets auto logged out while trying to upload large file

Hello Team,

I am unable to upload large file size via Serv U Portal. When attempted to upload the large file, after about 60% of upload, the progress bar disappears and after sometime, I receive a pop-up stating "Unauthorized - You have been logged out." and the file doesn't get uploaded.

Below is the screenshot of the developer tools error received during that moment:

Requesting urgent assistance on this.