Not serving/connecting on Android 9

[dwdvIl]

The server starts (onStart called) but it's not visible to any WebSocket clients, not even in the same phone. Error callback is not called.
Creating the server works on a different Android version, but connecting the Android 9 device to it doesn't work either.
It's not a WebSocket client problem, since connecting to a test server works.

Test Codes:

• Server:

wsserver.start(5457, {
      'onFailure': console.log,
      'onOpen': onClientConnected,
      'onMessage': onClientMessage,
      'onClose': onClientDisconnected,
      'tcpNoDelay': true
   }, function onStart(addr, port) {
     console.log('Server started.', addr, port);
   }, function onDidNotStart(reason) {
     console.log('Server not started. Reason: ' + reason);
 });

• Client (connecting to local server):

client = new WebSocket('ws://192.168.x.xxx:5457');
  //readyState: CLOSED, code: 1006

• Client (connecting to test server):

client = new WebSocket('wss://demo.piesocket.com/v3/channel_1?api_key=oCdCMcMPQpbvNjUIzqtvF1d2X2okWpDQj4AwARJuAgtjhzKxVEjQU6IdCjwm&notify_self')
//message: {"info":"You are using a test api key"}