I’ve attached my test project to FB21240977. After unzipping it, navigate into the folder and run the following command: $ swift run Thanks!

I haven’t used NWConnection before, so I couldn’t verify whether it has the same issue. However, this problem does not occur when using URLSessionWebSocketTask. As you suggested, I’ve reported what appears to be a bug through Feedback Assistant: https://feedbackassistant.apple.com/feedback/21240977