1. Prepare by lowering DNS TTL for your domains (`matrix.DOMAIN`, etc.), so that DNS record changes (step 4 below) would happen faster, leading ot less downtime
2. Stop all services on the old server and make sure they won't be starting again. Execute this on the old server: `systemctl disable --now matrix*`
3. Copy directory `/matrix` from the old server to the new server. Make sure to preserve ownership and permissions (use `cp -p` or `rsync -ar`)!
4. Make sure your DNS records are adjusted to point to the new server's IP address
5. Remove old server from the `inventory/hosts` file and add new server.
6. Run `ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start`. This will create the matrix user and group and start all services on the new server