MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017

Hello, I am having trouble getting connected to my localhost MongoDB on Mac OS. I have read through countless forums and tried everything to get mongod and the mongodb-community server started, but nothing has worked. The error I am getting is below:

  const serverSelectionError = new ServerSelectionError();
                           ^

MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017`

Can anyone help me with this please?

Is your mongod up and running on port 27017?
Can you connect by another tool like shell or Compass?