mongodb not working after Lightsail MEAN instance upgrade

Create a new Lightsail MEAN instance(2GB ram) using snapshot from another Lightsail MEAN instance (512mb ram). Both instances are in same region. Everything working as except mongo db.

I am getting this error when trying to connect to MongoServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017

I tried to start mongo - sudo service mongodb start and getting below message Failed to start mongodb.service: Unit mongodb.service not found.

mongo was working in the previous instance. Should we do anything else after creating an instance from snapshot?

Any help is truly appreciated.