Cannot connect to WebSocket server

Prerequisites

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[X] I have searched existing issues to ensure the bug has not already been reported

Fastify version

4.20.0

Plugin version

8.2.0

Node.js version

18.17.0

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

13.4

Description

I have tried in many different environments (Replit, Stackblitz, locally, with and without ESM enabled), but I just cannot seem to be able to connect with a WS server created with this plugin. Network time in DevTools is stuck on "Pending".

Steps to Reproduce

I copied the example from the docs for the server:

const fastify = require('fastify')();

fastify.register(require('@fastify/websocket'));

fastify.register(async function (fastify) {
  fastify.get(
    '/',
    { websocket: true },
    (connection /* SocketStream */, req /* FastifyRequest */) => {
      connection.socket.on('message', (message) => {
        // message.toString() === 'hi from client'
        connection.socket.send('hi from server');
      });
    }
  );
});

fastify.listen({ port: 3000 }, (err) => {
  if (err) {
    fastify.log.error(err);
    process.exit(1);
  }
});

Then I try to connect within DevTools:

new WebSocket('ws://localhost:3000');

ws

When I try the basic example from the ws package, it works instantly (after enabling ESM):

import { WebSocketServer } from 'ws';

const wss = new WebSocketServer({ port: 8080 });

wss.on('connection', function connection(ws) {
  ws.on('error', console.error);

  ws.on('message', function message(data) {
    console.log('received: %s', data);
  });

  ws.send('something');
});

Video demo

https://github.com/fastify/fastify-websocket/assets/876666/2031e15f-a88e-4cb8-9525-01826befe8f7

Expected Behavior

I would expect to be able to connect to the WS server.

fastify / fastify-websocket