504 Gateway error after launching new AWS instance

[IAmGav (Gavin Perch)]

here is a post you can check that might help you

Change the domain name or rename my Discourse?

This guide is for self-hosted Discourse instances that were installed using our installation guide on GitHub. If you are hosted by Discourse, please see Configure your domain name for hosted Discourse for specific instructions. You may eventually want to change the domain name of your Discourse instance, from say =BEFORE= → =AFTER= Let’s get started. Set the TTL for your DNS low, and in advance You need to let everyone know that the domain is about to change, so change the TTL f…