Hi Frank,
Sorry for the inconvenience caused.
I have created sample for your requirement. The sample which I have created is for when dragged and dropped the Connector Symbol from Symbol Palette, will connect the Symbols in a diagram. In order to achieving the above, we should set the 'EnableCentralPort' Property for the Symbols to true.
In our sample we want to connect the Rectangle node and Ellipse node using Connector Symbol. In order to achieving this, we should set the 'EnableCentralPort' Property of Rectangle and Ellipse Symbol to true. And also set the 'EnableCentralPort' Property of Connector Symbol to true in property editor.
For more details please refer the sample.
http://files.syncfusion.com/support/Diagram.Windows/Forums/F82618/main.htmRegards,
Gowri