https://www.tenforums.com/software-apps/16594-net-3-5-framework-cannot-install-0x800f081f.html
dism /online /add-package /packagepath:G:\sources\sxs\microsoft-windows-netfx3-ondemand-package.cab
Install Dotnet 3.5 on win 10
it's notes
“Tell me and I forget, teach me and I may remember, involve me and I learn.” ― Benjamin Franklin.