Written 28 Aug 2026. This is a how-to, not a product card.

Keep Wi-Fi off after a reboot

After the cable works, stop Wi-Fi from coming back so the computer keeps one address. You don't need a new router.

You plugged the cable. SSH from the couch worked. Then the computer rebooted for weekly fixes, and Wi-Fi woke up again. Now the computer has two numbers: one on the cable, one on the radio. SSH hangs. Pi-hole is flaky. That is not a broken router. The computer is answering on two doors. Full symptom walk: when the old PC has two house addresses. You are not buying a mesh kit for this.

Skip until the cable works

If the computer is still only on house Wi-Fi, stop. Plug a cable first: a cable beats Wi-Fi for the computer. That note also turns the radio off for this session, as a check. This note is the next step: make that stay off after a reboot. Never joined house Wi-Fi, and there is no cable? That walk is put the old PC on house Wi-Fi. If you cannot log in from the couch, that is SSH from the couch. Skip this note if it is a desktop or OptiPlex with no Wi-Fi radio.

What this is

The one-session off in a cable beats Wi-Fi for the computer is sudo ip link set wlan0 down. That lasts until the computer reboots. After a reboot, Wi-Fi often comes back by itself. Two numbers is how people lose SSH, and how a DHCP reservation on the cable address looks like it failed. This look asks Wi-Fi to stay off.

See if Wi-Fi is even there

SSH in from the couch, then run:

ip -br link

Look for a line whose name starts with wlan or wlp. That is Wi-Fi. The cable line often starts with en or is named eth0. If you see no radio line, you are done. An old desktop can skip the rest.

Turn it off so it stays off

Ask whether the computer has NetworkManager:

command -v nmcli

If that prints a path, turn Wi-Fi off this way. It usually survives a reboot:

nmcli radio wifi off

Then confirm:

nmcli radio

You want the WIFI line to say disabled or off.

If nmcli is missing, use rfkill instead. rfkill is the radio switch. On Debian and Ubuntu, that block usually survives a reboot:

sudo rfkill block wifi

Then confirm:

rfkill

The Wi-Fi (wlan) line should say Soft blocked. If the computer only understands the older list command:

rfkill list

Confirm the cable is the only door

Ask again:

ip -br link

The radio line should say DOWN. The cable line should stay UP. Then check the computer still has one house number:

hostname -I

You want one 192.168.… or 10.… address, not two. If SSH from the couch still works after that, you are done. Don't reboot just to prove it tonight. The next reboot (weekly fixes, or after a reboot, check the computer still does its jobs) is the real test. After that reboot, run ip -br link again. The radio should still be DOWN.

If Wi-Fi comes back anyway

Some old laptops turn the radio back on after a reboot. Try the other command from the pair above (nmcli if you used rfkill, or rfkill if you used nmcli). Then check again. Don't blacklist kernel modules tonight. Don't buy a new router because the computer grew a second number.

What next

Write down the computer's one remaining number: see the computer's address on the house network. Then keep that number: keep the computer on the same number. Cable speed stays see the cable speed. Skip a mesh kit and a new router for this look.

Skip

• Skip this note if the computer has no Wi-Fi radio. An old desktop or OptiPlex often does not.
• Skip if the computer is still only on house Wi-Fi. Plug a cable first: a cable beats Wi-Fi for the computer.
• Skip if SSH from the couch does not work yet. That is SSH from the couch.
• Skip buying a mesh kit or a new router because SSH hops between two numbers.
• Skip blacklisting kernel modules tonight.
• Skip opening SSH to the internet.