If you're using MongoDB Atlas, you can allow connections only from a specific subnet. Also, you should of course set a password or use x.509 certs. If you're

If you're using MongoDB Atlas, you can allow connections only from a specific subnet. Also, you should of course set a password or use x.509 certs. If you're hosting your own DB on a cloud provider, connect using a VPC / Heroku's Private Space Peering to keep your database off of the internet.