Installing .NET Framework 3.5 (which includes .NET 2.0 and 3.0) on Windows 10 and 11 usually requires an internet connection via Windows Update. To perform a truly offline installation, you must use the original Windows installation media.

Execute the Command: Replace D: in the command below with your actual drive letter:DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs.

dism /online /enable-feature /featurename:netfx3 /all /source:D:\sources\sxs /limitaccess

• Open Command Prompt as Administrator.
• Run: C:\temp\dotnetfx35.exe /layout:C:\temp\dotnet35 (This extracts files to C:\temp\dotnet35 without installing).