How can I use websocket to connect?

cocos2d-x JavaScript
#1

I am using cocos2d-x v3.17.2. I create a Network class to connect with my local server through websocket as below. When I build an android app, I keep getting the error of connection failed.

var Network = cc.Class.extend({
  _ws: null,
  ctor: function() {
  },
  connect: function(serverUrl) {
    this.connectToWebSocket(serverUrl);
  },
  connectToWebSocket: function(serverUrl) {
    this._ws = new WebSocket(serverUrl, []);
    this._ws.onopen = this.onOpen.bind(this);
    this._ws.onmessage = this.onMessage.bind(this);
    this._ws.onclose = this.onClose.bind(this);
    this._ws.onerror = this.onError.bind(this);
  },
  onOpen: function(event) {
    cc.log("onOpen");
    this._ws.send("Hello WebSocket, I'm a text message.");
  },
  onMessage: function(event) {
    console.log('WebSocket message received:', event);
  },
  onClose: function(event) {
    cc.log("onClose: ", JSON.stringify(event)); 
  },
  onError: function(event) {
    cc.log("onError: ", JSON.stringify(event));
  },
  onDestroy: function() {
    if(this._ws) {
      this._ws.close();
    }
  }
})
#2

Since I am using an actual device, I need to find the local IP of my server in the network, not using localhost.