Cannot create ws server on Ubuntu 16.04 on Google Cloud

[TangMonk]

in index.js, I have add a debugger breakpoint at following lines:

    const subscribers = {};                                                   // Map: debug session -> [ subscriber ]
    const tv = new Hapi.Server();
    tv.connection({ host: settings.host, address: settings.address, port: settings.port });

    tv.start(() => {
        const ws = new Ws.Server({ server: tv.listener });
        ws.on('connection', (socket) => {
debugger
            const subscriptions = {};

this above debugger never trigger, when I am using telnet 127.0.0.1 8888(I defined port as 8888) to connect socket, But if I change the the ws connection to specify port instead of tv.listener, it works

Not works on google cloud, but works on my mac