我正在尝试使用SSH（Putty）运行nextjs应用程序
登录后，我导航到应用程序的根目录并运行

screen -S screen_name

要在此之后启动新屏幕，我运行：

npm run start

然后我得到这个

> @iso/next@4.0.0 start
> NODE_ENV=production node server.js

> Ready on http://localhost:3200

但是当我试着在网上看应用程序时，它显示如下：

The connection has timed out

下面是server.js文件：

const { createServer } = require("http");
const { parse } = require("url");
const next = require("next");
const dev = process.env.NODE_ENV !== "production";
const hostname = "localhost";
const port = process.env.port || 3200;
// when using middleware `hostname` and `port` must be provided below
const app = next({ dev, hostname, port });
const handle = app.getRequestHandler();
app.prepare().then(() => {
createServer(async (req, res) => {
try {
  // Be sure to pass `true` as the second argument to `url.parse`.
  // This tells it to parse the query portion of the URL.
  const parsedUrl = parse(req.url, true);
  const { pathname, query } = parsedUrl;
  if (pathname === "/a") {
    await app.render(req, res, "/a", query);
  } else if (pathname === "/b") {
    await app.render(req, res, "/b", query);
  } else {
    await handle(req, res, parsedUrl);
  }
} catch (err) {
  console.error("Error occurred handling", req.url, err);
  res.statusCode = 500;
  res.end("internal server error");
}
}).listen(port, (err) => {
if (err) throw err;
console.log(`> Ready on http://${hostname}:${port}`);
});
});

我对另一个NextJS应用程序做了同样的事情，我能够运行它，没有任何问题
我做错什么了吗？