Setting up my home network the slow way

Everything in my apartment was on one flat network: my laptop, the client staging server, a smart plug from a brand that no longer has a website. Any one of those could talk to any other. The smart plug in particular had no business talking to anything.

Three networks instead of one

Personal for the machines I care about, IoT for the machines I do not trust, guest for visitors. Simple on paper. The trick was doing it one segment at a time over three weekends instead of one heroic evening, because the network also has to keep working for the people who live here.

Start with guest — nothing depends on it, so a mistake costs nothing. Then IoT, where the worst case is that a lamp stops responding. Personal last, once the pattern is proven.