Don't know all the details of the service but you probably could also have used haproxy causing no changes on the production servers (change server to proxy).

Don't know all the details of the service but you probably could also have used haproxy causing no changes on the production servers (change server to proxy). First install and configure haproxy to forward eerything to your existentiële environment. Change dns to the haproxy box. Add the new server to haproxy and remove the current one. Move DNS from haproxy to new server.