On Windows 7 with Mumble client 1.2.3, Mumble does not automatically re-connect after the computer is put into sleep or hibernate mode. It is a desktop machine, so it is (essentially) never without internet, however every time I resume from sleep Mumble says a single line:
[6:37:29 AM] Server connection failed: The remote host closed the connection.
And stops trying. This is irritating, as every time I suspend my PC I have to Server --> Connect --> Connect. My expected behavior in this scenario would be Mumble's ordinary behavior on disconnect: auto-retry until canceled or success.