Tried installing the grandnode in AWS. But getting the below error while setting up the store when entering DB connection details

Command saslStart failed: Authentication failed..

But with the same credentials I am able to connect to the instance using MongoDB Compass

It looks like you've missed something in installation process. Maybe the wrong password, username, or host, maybe blocked IP in MongoDB config.  It's hard to predict, because it's a default MongoDB exception.

But within the same ec2 instance, I have used a Mongo Client and have successfully connected to the DB.

No worries, I will try for some other solutions from my side.

In-case, if you find any solution/issue for this, please let me also know

I got an update on this. I am not sure why this error occured because , i am basically a beginner on Mongo.

When I set the connection string mongodb: //root:rootpassword@192.168.100.1/Webdev?authSource = admin,
it solved the error.

I was able to connect to DB with any client. Unfortunately error happened only when installing GrandNode. I am not sure if this can be addressed in you code.  

I just posted this solution, in this thread for others who may face this issue.