First, Enable hidden setting to include S3 uploads in the backups
Then make a backup. Then restore it. I recommend restoring it on a fresh server. You can use your existing yml file, but delete USE_S3, the upload bucket and the stuff that uploads assets to S3.
You Move a Discourse site to another VPS with rsync so that you’ll have your SSL certificates. I’d `–exclude postgres_*".
Then you can Restore a backup from the command line.