How much does changing the subdomain/domain break things?

[Moin]

There is also a guide about this

Change the domain name or rename your Discourse

This guide explains how-to change the domain name of your Discourse site, and includes information about setting up DNS changes, editing configuration files, updating site settings, and correcting social logins and post content to reflect your new domain name. 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 …