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Written 7 Sep 2026. This is a how-to, not a product card.

Flush old DNS on phones and laptops

After you point the router at Pi-hole, phones and laptops may still use the old DNS. Renew the Wi-Fi lease or flush the cache so ads drop. You don't need a new router.

Haven't pointed the house at the ad block yet? Start with point common home routers at Pi-hole (or the short pass: point the house at the ad block). Router will not take custom DNS at all? Set one device by hand: point a phone or laptop at Pi-hole when the router won't. One phone still dirty while everyone else is clean, and Private DNS or a VPN is on? That is when one phone still shows ads. This note is only the sticky-lease fix after DNS on the router (or on this device) is already right.

Skip until the router (or this device) already points at Pi-hole

If the gateway still hands out ISP DNS, flushing the phone will not help. Fix the router first. If nothing loads on any device after you changed DNS, put the router back on automatic so dinner works, then fix the computer: when the house won't browse after Pi-hole. Admin page blank? when the Pi-hole admin page won't open.

What this is

A phone or laptop remembers which DNS it got when it joined Wi-Fi. You change the router so new leases point at the computer. That device keeps the old lease for a while. Ads stay. Sites that should resolve through Pi-hole still hit the ISP. The fix is renew the lease, forget and rejoin house Wi-Fi, or flush the local DNS cache. Same idea after an ISP tech swaps the gateway: when the ISP swaps your router.

Step 1: prove the device still has old DNS

On the sticky phone or laptop, open the house Wi-Fi details and look for DNS / Name servers. You want the computer's house address (the one Pi-hole uses), not only the router's address or 8.8.8.8 / 1.1.1.1.

On Windows, in Command Prompt or PowerShell:

ipconfig /all

Find the active Wi-Fi or Ethernet adapter. Read DNS Servers. On a Mac, System Settings → Network → Wi-Fi → Details → DNS, or in Terminal:

scutil --dns | head

If the list still shows only the ISP or a public resolver, keep going. If it already shows the computer and ads remain, skip ahead to Private DNS / Relay / VPN checks in when one phone still shows ads or when one laptop still shows ads.

Step 2: iPhone or iPad

Open Settings → Wi-Fi. Tap the info button next to the house network. Tap Forget This Network. Join the house Wi-Fi again with the usual password. Open a site that used to show ads.

If you do not want to retype the password, toggle Airplane Mode on for ten seconds, then off. Or reboot the phone. Either renews the lease on most iOS builds. Stay on the main house SSID, not guest Wi-Fi.

Step 3: Android

Open Settings → Network & internet (or Connections) → Wi-Fi. Open the house network. Forget / Remove, then join again. Or tap the gear, forget, reconnect. Toggle Airplane Mode if Forget is awkward.

Also open Private DNS. Set it to Off, or Automatic if Off is missing and Automatic still uses the router. A hostname like dns.google or one.one.one.one skips Pi-hole on purpose. That bypass walk is when one phone still shows ads.

Step 4: Windows laptop

Open Command Prompt or PowerShell as your normal user:

ipconfig /flushdns

Then renew the lease on the active adapter:

ipconfig /release

ipconfig /renew

Check DNS again with ipconfig /all. You want the computer's address under DNS Servers. Chrome, Edge, or Firefox may still use Secure DNS / DoH and skip the house book. Turn that off for house Wi-Fi, or use the laptop walk: when one laptop still shows ads.

Step 5: Mac

In Terminal:

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

Type your Mac login password when asked. Nothing prints when it works.

Then renew DHCP: System Settings → Network → Wi-Fi → Details → TCP/IP → Renew DHCP Lease. Or forget the house network and join again. Confirm DNS under Details → DNS shows the computer's address.

Step 6: prove it in Pi-hole

On another device that already blocks ads, open http://pi.hole/admin (or the computer's address plus /admin). Watch Query Log. Use the sticky phone or laptop for a minute. You should see that device's lookups. Browse a site that used to show ads. Ads should drop.

If the log stays quiet while pages load, the device is still asking someone else. Go back to Wi-Fi details, Private DNS, Private Relay, Secure DNS, or a VPN. Full single-phone walk: when one phone still shows ads.

What this is not

This is not changing router DNS again. It is not wiping Pi-hole lists. It is not a reason to buy a mesh kit. It is not opening the admin page past the house network. It is not fixing a phone that bypasses house DNS on purpose with Private DNS, Private Relay, or a VPN.

What next

Router menus for the whole house: point common home routers at Pi-hole. Router will not take LAN DNS? point a phone or laptop at Pi-hole when the router won't. Ads still house-wide after leases look right? When ads come back. Admin opens but totals stay at zero? When Pi-hole shows no queries. ISP just swapped the gateway? When the ISP swaps your router. Watch the log: see what Pi-hole blocked. Once a week, keep Pi-hole updated.

Optional: jot which device still held old DNS in Lab plan — username + passkey, no email. Skip if you just want to keep reading.

Skip

Sources

Pi-hole docs. Pi-hole: generic router guidance. Microsoft: ipconfig. Apple: renew DHCP lease. Official pages only. For install, see the first useful thing. For router DNS, see point common home routers at Pi-hole. For a single bypassing phone, see when one phone still shows ads.

Also on this topic

Point common home routers at Pi-holeWhere to set DNS on TP-Link, ASUS, eero, Netgear, Nest, and ISP gateways so the house asks Pi-hole. Prefer LAN DHCP DNS. You don't need a new router. Point the house at the ad blockAfter Pi-hole is installed, point the house router at the computer for DNS. Phones and laptops need no app. Sites still load. A lot of ads don't. Point a phone or laptop at Pi-hole when the router won'tWhen Nest, Google Wifi, or an ISP gateway will not take custom DNS, set DNS on one phone or laptop so it asks Pi-hole. You don't need a new router for this device. When ads come backAds are back, sites won't load, or a phone still shows banners. Check the computer, Pi-hole, router DNS, then the phone. When one phone still shows adsEveryone else's ads dropped. One phone still shows banners. Check Private DNS, Private Relay, a VPN, then the Wi-Fi lease. You don't need a new router. When one laptop still shows adsEveryone else's ads dropped. One laptop (or one browser) still shows banners. Check Chrome, Edge, or Firefox Secure DNS, Windows encrypted DNS, Mac Private Relay, then a VPN. You don't need a new router. When the ISP swaps your routerTech left a new gateway (or reset yours). Ads are back, and SSH may miss the old address. Re-find the computer, re-point DNS, re-do the reservation. You don't need a new router or a new Pi-hole. When Pi-hole shows no queriesAdmin opens, totals stay at zero, query log empty. Prove the house asks the computer for DNS, then check Pi-hole status. You don't need a new Raspberry Pi. When the house won't browse after Pi-holePhones say no internet, or every site times out, after you pointed the house at Pi-hole. Put router DNS back on automatic so dinner works, then fix the computer. You don't need a new router. See what Pi-hole blockedOpen the query log (or watch it over SSH) so you can tell ads are dying, which device asked, and which name to allow later. You don't need a new router. The first useful thingPut a house-wide ad block on the old PC. The rest of the house keeps using the internet as usual. You don't need a Raspberry Pi. When guest Wi-Fi still shows adsGuest Wi-Fi is a separate network on purpose. Leave guests on ISP DNS, put a visitor on the main house Wi-Fi, or point guest DNS at Pi-hole only if they can reach the computer. You don't need a new router.