With Windows 10 alot of people run into the problem that when they, or some software, needs to install .NET 3.5 it claims it cannot download the files. There is a “simple” fix to this issue by running the installer directly from the Windows CD using an Elevated command prompt with the following command:
Dism /online /enable-feature /featurename:NetFX3 /All /Source:D:\sources\sxs /LimitAccess