Correct routine if updating server internal IP and DNS name (Monolith)

Is there a process to follow should a server's internal IP or external DNS name change? I have a situation where I want to set up a dummy snapshot of another server for troubleshooting. I've updated environment configs and run update-config with restart of services but there still seem to be services refusing to start (pgbouncer is one).

Is there a preferred process to follow to get a server back up after an IP change (internal) / DNS name change?