Written 24 Aug 2026. This is a how-to, not a product card. Buy links are not tagged yet.

A cable beats Wi-Fi for the leftover box

Once the leftover box is doing real work, plug it into the router with a cable. House Wi-Fi can wait. Skip this if it is already on a cable.

The leftover box should use a cable, not house Wi-Fi, once it is doing real work. Real work means SSH from the couch, or Pi-hole answering names for the house. Ethernet is the cable with the click. Wi-Fi is the radio. A leftover laptop often stays on the house radio. That is fine for a first install. It is a poor fit once the box has a job.

Why a cable

Wi-Fi drops when the laptop lid is shut, when the box roams to another access point, or when the radio sleeps to save power. A cable stays up. Pi-hole is house DNS, the phone book that turns names into numbers. If the leftover box vanishes, phones stop loading pages. SSH dies too. The box is not off. The radio just went quiet.

Skip this if the leftover is already on a cable

If the leftover is already plugged into the router, or into a switch, with a cable, skip this note. A desktop, OptiPlex, or mini PC often already is. You do not need to unplug a working cable to read this.

What you need

Any leftover Ethernet cable. Cat5 is fine. Plug one end into the leftover box. Plug the other end into a LAN port on the house router, not the WAN or internet port. LAN is a house port. WAN is the port that faces the street. Do not buy a new switch this weekend. The extra-fast ports can wait. Those later notes live under Faster network, starting with a faster switch for a first home lab.

How to tell it worked

On Debian or Ubuntu, on the leftover box, look at the plugs:

ip -br link

Or look at the route the box is using:

ip route

Look for an eth0 or enp address, not only wlan0. The cable name is often eth0, or it starts with enp. The radio is often wlan0, or it starts with wlp. The cable line should say UP. The route should go out that cable name.

Then turn Wi-Fi off as a check. Use the radio name you just saw. If it is wlan0:

sudo ip link set wlan0 down

SSH from the couch should still work, with the number from find the leftover box on the house network. If SSH dies, the cable did not take. Check the click in both jacks, and that you used a LAN port, not WAN.

Bring the radio back if you still need it:

sudo ip link set wlan0 up

If the radio is not named wlan0, swap in the name from ip -br link.

Leave Wi-Fi off

Once the cable works, leave Wi-Fi off. The leftover box then has one address. Two numbers, one on the cable and one on the radio, is how people lose the box after a reboot. Find the leftover box on the house network is easier with one number.

What next

If the leftover is a laptop, keep it awake when the lid closes. That is don't let the leftover laptop sleep. If Pi-hole is not up yet, that is the first useful thing on the leftover box. Once a week, keep the leftover box updated. Do not buy a NAS. Do not buy a 2.5G switch for this.

Skip

Skip this note if the leftover is already on a cable. Skip a new switch, a mesh kit, and a NAS this weekend. Skip buying Cat6 because Cat5 was in the drawer. The extra-fast ports can wait.