How can I link the nodes from node inner panel?

There are some labels and buttons which are implemented with “panel” in my node template. As a link from a node to another, it always connects from the whole node template border. I want to connect from inner panel border of a node template. Is there any properties of node or panel available to this?

Declare that Panel to be a “port” by setting its GraphObject.portId property to be a string. Probably you want this:

    $(go.Panel, ...,
        { portId: "" },

Please read more about ports: