Written 6 Sep 2026. This is a how-to, not a product card.

When the old PC has two house addresses

SSH works on one number, Pi-hole or the reservation on another — Wi-Fi and the cable both live. Keep one link. You don't need a new router.

Can't reach it at all? Start with find it on the house network, then when SSH won't connect. Cable plugged in but dark? That is when the cable is plugged in but there's no link. This note is the quieter mess: the computer answers on two doors at once, so the address you saved for SSH or Pi-hole keeps hopping.

Skip until you can log in somehow

You need a way onto the computer: SSH that still works on one of the numbers, or a keyboard and screen once. No login yet? SSH from the couch. Never joined house Wi-Fi and there is no cable? Put the old PC on house Wi-Fi. Desktop with no Wi-Fi radio? You usually only have one address — this page is not your night.

What this is

A house address is the number other devices use to reach the computer (often 192.168.… or 10.…). Wi-Fi and ethernet can each grab their own. After a reboot, or after you plug a cable without turning the radio off, both stay up. Your laptop still SSHs to last week's Wi-Fi number. The router reservation and Pi-hole sit on the cable number. Ads come back. SSH hangs. The computer is fine — it just has two doors.

Step 1: confirm you see two numbers

On the computer (SSH in with whichever address still answers, or use the keyboard), run:

hostname -I

Two (or more) house numbers on one line is the tell. One number and you are on the wrong page — go back to finding it or fixing SSH.

Then see which plugs are up:

ip -br link

The cable line often starts with en or is named eth0. The radio line often starts with wlan or wlp. If both say UP, that matches two addresses.

Optional detail on which number sits on which plug:

ip -br addr

Step 2: pick the door you want to keep

Prefer the cable when it has a working link. Plug into a LAN port on the house router (or a switch), not the WAN / internet port. Click both ends. Confirm the cable line is UP with ip -br link. First time moving off Wi-Fi? The plug walk is a cable beats Wi-Fi for the computer.

No cable that reaches, or no ethernet port? Keep Wi-Fi only. Unplug the cable if one is half-connected and confusing the picture. Stay on radio for now; a cable can wait until you can run one.

Step 3: turn the other door off for this session

If you are keeping the cable, take the radio down. Swap in the radio name from Step 1 if it is not wlan0:

sudo ip link set wlan0 down

If you are keeping Wi-Fi only and a cable interface is UP with its own address, take that cable interface down the same way (use the en… / eth0 name), or unplug the cable.

Check again:

hostname -I

You want one house number. SSH from the couch to that number. If SSH dies when you drop the radio, the cable never took — fix the link first (when the cable is plugged in but there's no link), then come back.

Step 4: make the choice survive a reboot

A one-shot ip link set … down often comes back after weekly updates reboot the box. If you kept the cable, make Wi-Fi stay off: keep Wi-Fi off after a reboot (nmcli radio wifi off, or sudo rfkill block wifi when NetworkManager is missing).

Then pin the one remaining number on the router so it does not drift: keep the computer on the same address on common routers, or the short pass keep the computer on the same number. Nest or an ISP gateway that will not reserve? Set one stable number on the computer: give the computer a fixed address when the router won't.

Step 5: point house jobs at the one number

Update anything that still remembers the old door: SSH bookmarks, Pi-hole LAN / DHCP DNS on the router (point common home routers at Pi-hole), and any phone or laptop you set manually (point a phone or laptop at Pi-hole when the router won't). Renew leases (toggle Wi-Fi on phones) after you change router DNS.

Ads still house-wide after that? When ads come back. Admin opens but the query log stays empty? When Pi-hole shows no queries.

What this is not

This is not a dead NIC, a new mesh kit, or opening SSH to the internet. It is not two Pi-holes. It is not blacklisting kernel modules on night one. Two addresses means two live links — pick one.

What next

Write down the surviving number: see the computer's address on the house network. Tired of typing digits? Add a local name in Pi-hole. Cable speed check later: see the cable speed. After the next reboot, glance once: after a reboot, check the computer still does its jobs.

Optional: jot the one address you kept in Lab plan — username + passkey, no email. Skip if you just want to keep reading.

Skip

• Skip a mesh kit or a new router because SSH hops between two numbers.
• Skip buying a second NIC or a USB ethernet dongle for this look.
• Skip blacklisting Wi-Fi kernel modules tonight.
• Skip opening SSH (or DNS) to the public internet.
• Skip this if the computer has no Wi-Fi radio and only one cable — you are not on this page.
• Skip this if you still have zero working login — fix SSH or the keyboard first.