https://dotnet.microsoft.com/en-us/download/dotnet-framework/thank-you/net481-offline
The .NET Framework is a software development framework developed by Microsoft that provides a large library of pre-built functionality, runtime environment, and a virtual execution environment for software applications. As of my last update, the latest version available is .NET Framework 4.8, with no 4.8.1 version officially released. However, I will guide you on how to download the .NET Framework 4.8 offline installer from Microsoft, which should meet your requirements. download .net framework 4.8.1 offline installer microsoft