我试图在服务器上部署Node.js + Angular应用程序，但socket.io停止工作，我无法接收任何数据。本地工作正常，但一旦我改变URL，我就不能再使用socket.io了。

服务器端

const app = express();
// socket.io
const httpServer = createServer(app);
const io = new Server(httpServer, {
  cors: {
    origin: "http://SERVERURL",
  },
});

io.on("connection", (socket) => {
  socket.on("custom-event", (data) => {
    io.emit("receive-message", data);
  });
});

dotenv.config();
const PORT = process.env.PORT || 3000;

app.use(express.json());
app.use(cors());

app.use("/users", usersRoutes);
app.use("/auth", authRoutes);

app.get("/", (req, res) => {
  res.send("Hello");
});

mongoose
  .connect(process.env.CONNECTION_URL)
  .then(() => {
  })
  .catch((error) => console.error(error));

httpServer.listen(PORT);

客户端

socket: Socket;
  socketSub = new Subject();
  constructor() {}

  passServer(data: any) {
    this.socket = io('SERVERURL', {
      transports: ['websocket'],
    });
    this.socket.emit('custom-event', data);
  }

  receiveServer() {
    this.socket = io('SERVERURL', {
      transports: ['websocket'],
    });
    this.socket.on('receive-message', (data) => {
      this.socketSub.next(data);
    });
  }

该错误在Firefox和Chrome中都出现。我没有任何特别的错误消息，只有：GET 400 BAD REQUEST - GET wss://URLSERVER/socket.io/?EIO=4&transport=websocket和Firefox can't establish a connection to the server at wss://URLSERVER
我测试与客户端在本地主机和服务器端部署在一个真实的的服务器上。