Troubleshooting MongoDB connection string

Here are some troubleshooting steps you can perform to debug a MongoDB connection string:

1. Check the syntax: Make sure that the connection string is properly formatted with the correct syntax. MongoDB connection strings typically start with mongodb://, followed by the hostname and port number, and end with the name of the database. 

2. Check the hostname: Ensure that the hostname in the connection string is correct and resolvable. Try pinging the hostname from within the host and container to ensure that it is accessible from your system.

3. Check the port number: Verify that the port number in the connection string matches the port number that MongoDB is listening on. By default, MongoDB listens on port 27017.

4. Check the authentication details: If your MongoDB instance is configured to require authentication, make sure that the username and password in the connection string are correct. You can test authentication by connecting to the MongoDB instance with a MongoDB client tool.

5. Check the firewall: Ensure that your firewall is not blocking the MongoDB port. If you're connecting to a remote MongoDB instance, make sure that the appropriate firewall rules are in place.

6. Check the MongoDB logs: Check the MongoDB logs for any errors or warnings that may be related to the connection issue. The MongoDB logs are typically located in the /var/log/mongodb/ directory.

7. Test the connection: Try connecting to the MongoDB instance with a MongoDB client tool, such as the mongo shell or a GUI tool like Robo 3T. This can help you identify any issues with the connection string or with the MongoDB instance itself.