Socket.IO客户端无法连接服务端问题求助（PHP环境）

我正在开发一个聊天站点，访问地址为http://localhost/Seminarska%20naloga%20NRSA/index.php?stran=chat。提交消息后服务端未接收消息，客户端甚至无法连接到运行在http://localhost:3000的服务端。当代码位于index.html文件中时，访问http://localhost:3000聊天功能可正常运行且无报错，但将代码放入名为chat.html.php的PHP文件后连接失败。

客户端HTML代码 #

<ul id="messages"></ul>
<form id="form" action="">
  <input id="input" autocomplete="off" /><button>Send</button>
</form>
<script src="/Seminarska naloga NRSA/template/node_modules/socket.io/client-dist/socket.io.js"></script>
<script>
const socket = io("http://192.168.88.152:3000");

var messages = document.getElementById('messages');
var form = document.getElementById('form');
var input = document.getElementById('input');

form.addEventListener('submit', function(e) {
    e.preventDefault();
    if (input.value) {
    socket.emit('chat message', input.value);
    input.value = '';
    }
});

socket.on('chat message', function(msg) {
    var item = document.createElement('li');
    item.textContent = msg;
    messages.appendChild(item);
    window.scrollTo(0, document.body.scrollHeight);
});
</script>

服务端Node.js代码 #

const express = require('express');
const app = express();
const http = require('http');
const server = http.createServer(app);
const { Server } = require("socket.io");
const io = new Server(server);

app.get('/', (req, res) => {
  res.sendFile(__dirname+'/chat.html.php');
});

io.on('connection', (socket) => {
  console.log('a user connected');
});

io.on('connection', (socket) => {
    console.log('a user connected');
    socket.on('disconnect', () => {
      console.log('user disconnected');
    });
  });

  io.on('connection', (socket) => {
    socket.on('chat message', (msg) => {
      console.log('message: ' + msg);
    });
  });

  io.on('connection', (socket) => {
    socket.on('chat message', (msg) => {
      io.emit('chat message', msg);
    });
  });

server.listen(3000, () => {
  console.log('listening on *:3000');
});

内容的提问来源于stack exchange，提问作者Zvezda1999