Written 27 Aug 2026. This is a how-to, not a product card. Buy links are not tagged yet.

See which name server the leftover box is using

When names fail or ads come back, check which DNS the leftover box asks before you buy a mesh kit.

DNS (the name server) is who the leftover box asks to turn a site name into a number. If that who is the ISP or the router instead of the leftover-box Pi-hole, house ads can come back on that box even when other phones look fine.

Skip until SSH works and Pi-hole is installed

If you have never logged in from the couch, that is SSH from the couch. If you never installed Pi-hole, start with the first useful thing on the leftover box. If you never pointed the house at that box, do that in point the house at the leftover-box ad block. If ads came back after it already worked, also see when ads come back, check the leftover-box ad block. This note assumes you can SSH in, and Pi-hole was already the plan.

What this is

A look, not a shopping trip. The house router may point phones at Pi-hole while the leftover box itself still asks the ISP. Check which name server the leftover box is asking before you buy a mesh kit. You are not buying Omada, UniFi, or a Protectli tonight.

Ask which name server the leftover box is using

SSH from the couch, then on Ubuntu or Debian with systemd-resolved:

resolvectl status

Point at DNS Servers and Current DNS Server for the house link (the ethernet or Wi-Fi line that is up). You want the leftover box's own Pi-hole address when that is the plan. That is often 127.0.0.1, or the house address from see the leftover box's address on the house network. If you only see the ISP or the router, that is the clue.

Optional older print

If you want the older one-file print:

cat /etc/resolv.conf

Look at the nameserver lines. If you see 127.0.0.53, that is systemd-resolved talking to itself. Use resolvectl status for the real name server. Keep this light. Do not edit resolved configs tonight.

What the look means

Wrong DNS means fix the pointing in point the house at the leftover-box ad block, or check that Pi-hole is still answering in when ads come back, check the leftover-box ad block. If a house job failed to start, that is see if any house jobs failed to start. Do not buy Omada or UniFi for this look. The admin password is a different note: change the Pi-hole admin password.

What next

Router points at Pi-hole: point the house at the leftover-box ad block. Ads check: when ads come back, check the leftover-box ad block. Admin password: change the Pi-hole admin password.

Skip

Skip if SSH fails. That is SSH from the couch.
Skip a mesh kit for wrong DNS.
Skip buying a Protectli.
Skip forwarding port 53.
Skip Proxmox tonight. That is what a VM is, and when you do not need one.

Sources

Debian: resolvectl. Debian: resolv.conf. Official pages only. For install, see the first useful thing on the leftover box. For router DNS, see point the house at the leftover-box ad block. For the ads check, see when ads come back, check the leftover-box ad block. For the house address, see see the leftover box's address on the house network. For the admin password, see change the Pi-hole admin password.

Also on this topic

When ads come back, check the leftover-box ad blockThe leftover box is awake, but banners are back. Check that Pi-hole is still answering before you buy a mesh kit or blame the router. Point the house at the leftover-box ad blockAfter Pi-hole is installed, tell the house router to ask the leftover box for names. Phones and laptops need no app. Sites still load. A lot of ads do not. Change the Pi-hole admin passwordAfter the house ad block is up, change the admin password the installer printed. That password is not the leftover-box login. The first useful thing on the leftover boxPut a house-wide ad block on the leftover box. The rest of the house keeps using the internet as usual. You do not need a Raspberry Pi.