If this is a bug then you need to do the proper reporting link to report this. Otherwise you should contact the site on how best to download large file as well.

https://support.mozilla.org/en-US/kb/file-bug-report-or-feature-request-mozilla

https://support.mozilla.org/en-US/kb/cant-download-or-save-files

If this is a bug then you need to do the proper reporting link to report this.

You generally need to figure out what the actual issues is first and reproduce it and such before filing a bug though.

From https://bugzilla.mozilla.org/page.cgi?id=bug-writing.html

If you can't reproduce the problem, there's probably no use in reporting it, unless you provide unique information about its occurrence.

Got an old Dell from my mom that used to have connection drops so one could not do video chat well or download larger files. It was dusty inside and once I blew it out with a electric duster it no longer had connection drops.

Thank you for your responses!

The network connection has been verified to be stable, with no drops observed.

The knowledge base article offers only general advice. Could there be a way to enable detailed logging to better understand the circumstances surrounding a download failure? With verbose logs, I could analyze the Firefox source code to better understand the issue, which would help me submit a comprehensive bug report -- provided that a bug is indeed the cause.

At any rate, the issue started at a certain point in time, was not present initially, and is occurring on multiple machines. I am uncertain if it was caused by an OS update, a Firefox update, or something else. However, I find it unlikely that security software is responsible, given that Chrome consistently completes downloads successfully.

Can we get proof of the issue? Screenshots and steps to replicate with links would help us help you.