Anytime you see "because the remote party has closed the transport stream." That means the client thats attempting to talk to your server closed the connection from their side. We don't usually know this occurs until we attempt to "read" or "write" back to that connection but since they abruptly closed the connection we get an exception.
So it's a problem caused by them closing their connection. While the error itself is a bit verbose and annoying you can usually ignore these but I'd check that client that's constantly trying to connect to you and failing as they may be trying to do something fishy. They may try to authenticate then bounce out after a few attempts.
We do have a slight issue that I believe we fixed with the IP UNKNOWN showing up however you should be able to look higher up in the log for session id `39839562` and there should be the initial connection with the IP included. Its just that specific error message that doesn't see the IP. What version are you on?