While Windows Server 2016 comes pre-installed with .NET Framework 4.6.2, it fully supports upgrading to .NET Framework 4.8. Using the offline installer (standalone redistributable) is the recommended method for servers with limited or no internet access, as it includes all necessary components in a single package (approximately 116 MB). Key Download Links
Since the server may not have internet access, you will likely need to download this file on a separate PC and transfer it via USB drive or network share. .net framework 4.8 offline installer for windows server 2016
File details you should verify: