A notebook about the ordinary things that make networks dependable: useful measurements, simple checks, and a way back when an experiment fails.
A listening port is only the first step. A useful check follows a request to its destination and verifies the response. Name the thing you actually measured.
Change one part, observe it, and keep a record. Clear experiments are easier to understand than a collection of simultaneous improvements.
A backup is more useful when its restoration has been tested. Write down what changed before the next person needs to investigate it.