In Network I have a drop down which says Location Automatic, I have never changed this.
Under that there is a drop down labeled Show; That is set to Network Status, it can be changed to Bluetooth, Built in Ethernet, Airport etc. Selecting one of those allows you to configure that type of device.
When its selected on Network Status it gives an overview of all enabled devices, for me that is Airport. When the Mac starts it says Airport is enabled but not connected to a network. I then select it, tell it to connect, it connects and its fine. Until I restart again and it looses it.