Three suggestions:

1. Try a different browser. I used to use Opera for files that were tricky to download successfully.

2. Wait till after business hours (off-peak hours). We're all sharing internet with millions more people now working from home. Bandwidth and speed can get really weird. Not just yours, MM's connections can be the culprit.

3. If not getting an error that the download has timed out, wait till if finishes or gives an error. Overnight if you have to — like in the bad old days.

Unfortunately, with the latest conditions, internet speeds and availability can be rather terrible. 

Thanks! Yes i thought it was a data speed problem. Stay safe.