How do I practice on my mini PC without risking the home network?

I'm close to getting a used mini PC and I'd like to practice Linux on it before I run anything the household depends on. My partner works from home and has video calls most days, so I really don't want to be the reason the Wi-Fi drops.

If I plug the mini PC into the same router as everything else, can a mistake on it take down the network? I think the risky part is anything that changes network settings, like a static IP or something that hands out addresses, but I'm not sure. Is it safe to just install Linux and mess around, as long as I don't touch the router? And is there a simple way to keep it separate until I know what I'm doing, without buying a managed switch?

@SamTinkers Short answer: a fresh Linux install is very unlikely to hurt anything. By default it's just a DHCP client, same as a laptop. The risk comes from what you run afterward.

Things that can disrupt a shared LAN:

• A second DHCP server (dnsmasq, Pi-hole with DHCP enabled, some VM tools). Clients can get the wrong gateway or DNS. This is the classic one.
• A static IP that collides with another device, or sits inside the router's DHCP pool.
• Bridged networking or a cable loop between two ports on an unmanaged switch.

Things that are generally fine: SSH, packages, Docker with its default NAT bridge, and VMs on NAT networking.

Without a managed switch, you have two options:

1. Router guest network. Many routers offer one, but isolation varies. Check the docs for client isolation, then test it by trying to ping a family device from the mini PC.
2. A cheap second router as a lab gateway. Its WAN port goes to your main LAN and the mini PC sits behind it on a different subnet. It's double NAT, which is fine for practice, but make sure the subnets don't overlap.

One habit that helps either way: use a DHCP reservation instead of a static IP on the host.

What router do you have? I'd check whether its guest network really isolates clients before relying on it.