I have the same issue. Large files (Proliant Support Pack) downloaded directly from HPE. When HTTPs is enabled, after 4.5 GB has been downloaded a network error is reported in the browser (Microsoft Edge) and the download stops and it won't recover.
I tried a number of different large ISO files from HPE, and they all failed after exactly 4,350,966K had been successfully downloaded.
I have two internal subnets. One has HTTPS inspection enabled and the other does not. All other settings are identical.
The large downloads work from the subnet that does not have HTTPS inspection enabled.
I have downloaded large ISO files from Microsoft, and these have worked OK. So it appears it's only certain sites that have the problem, but so far, I've not been able to find a pattern.
There's nothing in the Firewall logs that indicates any problems, nothing is blocked or dropped.
I have extended logging enabled for all web traffic.
I don't think this is new to R82. Pretty sure it occurred in earlier releases too.
I'm running R82 with the latest recommenced Jumbo Hotfix Accumulator.