It seems you are not calling your async mongo function. You are only declaring your function. You need to call it by placing () after your declaration like so:
(async function mongo() { // Your code})();So applying that change to your code would result in the following:
const express = require("express");const router = express.Router();const { MongoClient } = require("mongodb");/* GET Books page. */router.route("/").get((req, res, next) => { const url = "mongodb://localhost:27017"; const dbName = "Library"; (async function mongo() { let client; try { client = await MongoClient.connect(url, { useUnifiedTopology: true }); const db = client.db(dbName); const books = await db.collection("books").find().toArray(); res.render({ title: "Books", books, }); } catch (err) { console.log(err); } })();});module.exports = router;Because of this your request would indeed timeout as the code within the async function is not called.
Hope this answer was helpful 👍