How to Resume Interrupted Downloads on Mac
Resume only works if both sides agree: the server must accept range requests, and the client must remember how far it got. Browsers are inconsistent. A download manager is built around that contract.
Why the browser gives up
Chrome and Safari can resume some downloads, but a closed window, a redirected URL or a server without Range support usually forces a restart. There is no good per-segment view, so you cannot tell what failed.
How AVS resumes
AVS Download Manager stores segment state for each item. Open the download detail window to see per-segment progress, live speed and remaining time. If the link still answers range requests, tap resume and it continues. If the host issued a one-time URL, paste the fresh link and attach it to the same item when the app asks.