NodeJs MongoDB Connection Parameter Issue with Digital Ocean Managed MongoDb

I went through the tutorial, from start to finish, have a Digital Ocean Managed Mongo DB created, and am beating my head against a wall trying to get Node to successfully connect to the database. This is my connection code (sensitive values have been obscured):

let cachedDb = null;

  async function connectMongo() {
    if (cachedDb) {
      return cachedDb;
    }
    try {
      const url = 'mongodb://doadmin:****************@db-mongodb-****-*****-********.mongo.ondigitalocean.com/admin?authSource=admin&replicaSet=db-mongodb-****-*****'
      const client = await mongodb.connect(
        process.env.DATABASE_URL, {
          useNewUrlParser: true, 
          useUnifiedTopology: true,
          // tls: true,
          tlsCAFile: './ca-certificate.crt'
        }
      );
      const db = client.db('nanocrowd');

      cachedDb = db;
      return db;
    } catch(err) {
      console.log(err);
      throw(err);
    }
  }

When the code attempts a connection, the following error response is returned:

stack: 'MongoServerSelectionError: getaddrinfo ENOTFOUND db-mongodb-****-*****-********.mongo.ondigitalocean.com\n    at Timeout._onTimeout (node_modules\\mongodb\\lib\\sdam\\topology.js:325:38)\n    at listOnTimeout (internal/timers.js:554:17)\n    at processTimers (internal/timers.js:497:7)'

I’m able to connect to the managed mongodb instance from my local development machine using two different clients: mongo, and Compass. Both connect using the identical parameters supplied to the NodeJS connection.

Does anyone have a working example that they’re willing to share?

Thanks in advance.