@DTS Engineer Thanks for your response. I tried to implement NWListener.newConnectionGroupHandler, but not called... So I guess another relates to problem. I found weird log. The operation couldn’t be completed. (Network.NWError error 50 - Network is down) It seems that NWConnectionGroup.state turns .waiting with the NWError above just after .ready. _group.stateUpdateHandler = { state in switch state { case .waiting(let e): // `waiting` is called 100ms after `.ready` // The operation couldn’t be completed. (Network.NWError error 50 - Network is down) print("\(e.localizedDescription)") case .ready: print("ready") default: break } } Of course, Network is not down. I can use everything on the Internet on debug device. How should I do to fix? or Do you have any idea for NWListener.newConnectionGroupHandler is called? Device Info iOS Simulator/iOS18.2 Xcode 16.3

@DTS Engineer forget to write. logs below still displayed although I implemented NWListener.newConnectionGroupHandler nw_protocol_instance_add_new_flow [C1.1.1:2] No listener registered, cannot accept new flow quic_stream_add_new_flow [C1.1.1:2] [-fde1594b83caa9b7] failed to create new stream for received stream id 3

@DTS Engineer I tried NWConnection instead of NWConnectionGroup, but still NO listener registered is displayed. Any ideas to solve? I am completely cornered. I will do to solve whatever it takes.