"Connection to Microsoft exchange is unavailable" is a common and annoying error that you get when you use Outlook. Here are some ways to fix it. Introduction. Remote Procedure Call (RPC) is an inter-process communication technique to allow client and server software to communicate on a network. Jan 16, 2012  · Comments on: "[Solved] WMI ConnectServer Access is denied , The RPC server is unavailable." (3) Server Fault is a question…