Connection errors after upgrading to MongoDB v4 Node.js driver


After upgrading from MongoDB v3 driver for Node.js to MongoDB v4 (latest version) and removing everything related to isConnected() and just following the documentation from here:
I keep on getting errors like these:
MongoNetworkError: connect ECONNREFUSED x.x.x.x:27017

Is this due to the fact that the mongodb driver does not re-connect back?

Have you experienced this before?

Thank you!