This is the most reliable method for Windows 10 and 11, as it uses the source files already present on your Windows ISO or DVD. How to manage .NET Framework on Windows 10 and 11 - PDQ
Even with an offline installer, several issues can arise: microsoft net framework 3.5 offline
In these cases, the —specifically the standalone executable dotnetfx35.exe or the use of the Deployment Image Servicing and Management (DISM) tool with a source media—becomes the only viable solution. This is the most reliable method for Windows