There's nothing wrong with the hub.
It's the user sending a connection request that doesn't have the proper syntax.
In this case the port is missing at the end: $ConnectToMe dikkedeur 87.66.173.106:
This technically is a bug in the client that it sends the $ConnectToMe command without all needed info.
You could contact the user to let him check his connection settings, to make sure that a port is properly set.