When I tried to look for more answers, I saw a reference that there's an "automatic cooldown". Whether that is true is another question. I started to believe that it may be because there is a NWConnection and listener.cancel() was used? Not sure if that causes issues for the socket to close, but when I look at the Client Connection, I do indeed see that trigger .cancel() kicks active connections out.

Yep, I am. It was one of the things that I've tried that I found through another Forum Post. I even tried settings some parameters that you actually can't set on the Listener, they were meant for a NWConnection. But I've tried setting theses, and it didn't seem to have any effect. params.allowLocalEndpointReuse = true // SO_REUSEADDR? params.includePeerToPeer = true params.acceptLocalOnly = true listener = try NWListener(using: params, on: port) listener?.start(queue: .main)