Should I call the CheckConnectionState instead if I don't want to have the keep alives sent?

Question

Another question is, when the server (FileZilla) shuts down, how come we are not getting the "421 Server is going offline" from the logger.

Answer 1

Yes, CheckConnectionState or GetConnectionState might be a better option in that case. However, if you used KeepAlive, you should actually be getting the server's shutdown message when you call the method after the connection has been shut down (if the server actually sent it). If you are not, a communication log might contain some clues about what was going on from the client's point-of-view.