Unable to install .NET3.5 from roles because of no internet connection?
Note: .NET 3.5 needed for SQL 2014 and other applications

Follow this guideline https://support.microsoft.com/en-ie/kb/2734782

In summary:

• Insert W2012R2 install disk
• Run CMD with Admin privileges
• Run the below command (change drive letter to correct DVD drive)

Dism /online /enable-feature /featurename:NetFx3 /All /Source:<drive>:\sources\sxs /LimitAccess

• https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-R2-and-2012/jj127250(v%3dws.11)
• http://askme4tech.com/install-and-configure-dfs-replication-windows-server-2012