The current state of the connection. One of:
- Closed - the connection was previously established but is no longer in use.
- Ready - the connection is active and ready to exchange data.
- ACK Pending - the connection is active, a message has been sent, and an acknowledgement is pending.
- Syncing - attempting to recover from connection errors between the two devices.
- Opening - the node was located correctly and the connection is opening.
- Unknown - the connection is in an unknown state.