installing Traefik or n8n itself on a machine connected to the network shouldn't break or impact any services.

but in the process of setting up your homelab to connect to them, you might misconfigure your network and "break" your services.

e.g. misconfiguring your DNS and suddenly your IPTV seems broken

I like keeping notes on the changes I do to the network. That helps me remember and undo my changes if necessary.

a switch is like a tube station for local traffic, essentially an extension lead

You're right, a basic unmanaged switch is basically that!

Managed switch is a smarter switch. For example, creating VLANs or doing port trunking.

These are generally configured on the switch GUI as you mentioned.

Think of them as a computer with dedicated software to control how the network interfaces behaves.