Yeah, you’ll definitely want to make sure that computer is isolated. It doesn’t sound like it’s currently on a VLAN. The real danger isn’t just someone messing up that one machine, once they’re in, they’re behind your firewall and can potentially access anything else on your network. Smart home devices are often the next targets, things like light bulbs, security cameras, and especially Windows computers, which are usually easy to compromise if they’re on the same network.

You might be wondering, “How likely is that?” Honestly, very likely. Back when my website was online, it would get hit by hackers, mostly script kiddies, several times an hour.