Unable to connect remotely to MySQL on Node.js image

Hello,
Thank you for using Lightsail.

That guide directs you to bind your MySQL server to localhost. Due to the network configuration of AWS, you need to use 0.0.0.0 in order to bind to external traffic (coming through your Public IP address).

If this is a server you use for a production application, in the interest of security it's recommended to keep the MySQL network port closed in your firewall and use SSH tunneling instead https://docs.bitnami.com/virtual-machine/faq/get-started/access-ssh-tunnel/

In that article, SOURCE means the local port you want to use to connect: ex 23306
DESTINATION is the address on the remote machine you want to reach: ex. 127.0.0.1:3306

Then you'd connect to localhost:23306 in HeidiSQL

Regards,
Gabriel