Node Lambda function accessing Aurora database times out with postgres

Question

I'm trying to write a Lambda function (in nodejs) which executes a simple SQL query. The database is an Aurora Postgres. I have set up function configuration for VPC access, worked fine with a MySQL database.

As you can see in the following, I'm using the "pg" node module (https://github.com/brianc/node-postgres). app.js

// For example, this function times out
const { Client } = require('pg');

const config = {
  user: '<MY_DB_USER>',
  host: '<MY_HOST>',
  database: '<MY_DB_NAME>',
  password: '<MY_DB_PASSWORD>',
  port: <MY_PORT>
};

var postgresClient = new Client(config);

module.exports.handler = (event, context, cb) => {
   console.log('entered handler');
   postgresClient
       .connect()
       .then(() => {
           console.log('connected');
           return postgresClient.end();
       })
       .then(() => cb())
       .catch(cb);
};

Yet, when using a postgres database, the lambda function times out every time I invoke. I have set up the subnets and the Security Group.

I have also tried using Pool from the pg module, with no success.

Note that this functions runs locally with success... I can't figure out why the lambda fails when it is deployed.