If you do have a weak Internet connection, are on WiFi, LTE or whatever this error can be corrected by trying the download again. Remember every device on your home network (including WiFi devices) will gobble up every byte. If you or people in your home are streaming something that will also impact your connction.
If you are hard wired (Ethernet cable) bad cables can cause intermittent issues with downloads. Old routers (or routers not updated), and so on can cause issues. I've never had issues with antivirus software screwing up downloads, but it can happen.
Your ISP could be capping your monthly bandwidth and you may have exceeded it. If it is, then you are at their mercy. Nothing we tell you will solve that problem.