const db = process.env.DB;
mongoose
  .connect(db, {useNewUrlParser: true})
  .then(() => console.log('connected'))
  .catch(err => console.log(err))

{ MongoNetworkError: connect ECONNREFUSED 18.194.103.39:27017
    at TLSSocket.err (/Users/alex/Documents/dev/WD/Projects/personal-library/node_modules/mongoose/node_modules/mongodb-core/lib/connection/connect.js:287:16)
    at Object.onceWrapper (events.js:277:13)
    at TLSSocket.emit (events.js:189:13)
    at emitErrorNT (internal/streams/destroy.js:82:8)
    at emitErrorAndCloseNT (internal/streams/destroy.js:50:3)
    at process._tickCallback (internal/process/next_tick.js:63:19)
  name: 'MongoNetworkError',
  errorLabels: [ 'TransientTransactionError' ],
  [Symbol(mongoErrorContextSymbol)]: {} }