"The Network Connection Was Lost" Safari

Hi.

I try to download a ZIP file of 500MB or higher.

Downloads take a long time and on Safari I get error "The Network Connection was Lost" all of a sudden

tried downloading on other software like Firefox and they work.

When "The Network Connection Was Lost" shows the internet still works.

Download speeds are fine, and my internet is still connected, tried resetting cache, SMC etc that doesn't work or hasn't helped.

What is causing this issue on Safari. tried everything. i'm going mad. please help thanks