Sounds mostly like an issue from the Host of the files end, But of course not nailed on, Sounds like a download from an iffy serverA few basic things you can check, that might indicate where the origin of the issue is:
1. Does your target Download folder have enough free disk space for the file?
2. What connection to your router does the computer have (WiFi or Wired Ethernet)?
3. When the Internet "crashes" do you have Green or Red lights lit up on the Router?
4. When Internet "crashes" does the Internet Icon on the Taskbar change?
5. Have you tried downloading the file at a different time of day, especially at an Off-peak time?
6. When you reboot the computer do you reboot the Router, too?