From
here:
(student) IT Technician working at a college here. Run into this problem just yesterday. After a few hours of diagnosing, we found out that the problem happens as long as there is an anti-virus installed. Disabling it does nothing, but uninstalling the anti-virus immediately allowed downloads to resume normally.
Upon careful investigation, it was found that the anti-virus's HTTP checking (port checking) option was responsible. Disabling this option permanently fixes the network error thing. Since only HTTP/Port-checking is disabled the anti-virus should still work normally