DNS Filtering at the Router vs Pi-hole: Which One Actually Blocks Ads and Threats on Your Home Network

DNS filtering is one of the cheapest, most effective layers of network protection you can add to a home network. It also generates more confusion than almost any other topic in home networking, mostly because there are three or four different ways to do it and the tradeoffs are genuinely non-trivial. This article breaks down the two main camps: filtering at the router using third-party DNS resolvers like NextDNS or Cloudflare for Families, versus running a self-hosted Pi-hole. Both block ads and threats at the DNS level. Neither blocks everything. The right choice depends on how much time you want to spend maintaining it.

What DNS Filtering Actually Does (and What It Cannot Stop)

Every time a device on your network loads a website or app, it first asks a DNS resolver to translate a domain name into an IP address. DNS filtering works by intercepting that lookup and returning either nothing or a harmless IP when the requested domain appears on a blocklist. The device never connects to the destination because it never gets a valid address.

This is effective against ads served from dedicated ad-serving domains, known malware distribution sites, phishing domains, and trackers that operate from their own domains. Pi-hole’s published documentation and independent analyses like those from The Block List Project confirm block rates of 10-30% of all DNS queries on a typical home network, depending on which blocklists are active.

What DNS filtering cannot stop: ads served from the same domain as the content (YouTube ads are the canonical example, since they come from googlevideo.com), HTTPS-level tracking baked into first-party domains, apps that hardcode IP addresses instead of using DNS, and DNS-over-HTTPS (DoH) traffic that bypasses your resolver entirely by tunneling DNS inside encrypted HTTPS. That last one is increasingly common. Firefox enables DoH by default, and Chrome pushes it aggressively. If you do not account for DoH, a meaningful percentage of your household’s DNS queries will never reach your filter at all.

Router-Level DNS Filtering: Built-In Options vs Third-Party DNS

Most consumer routers let you change the upstream DNS server in the WAN settings or DHCP configuration. Pointing that setting at a filtering DNS service is the lowest-effort approach available.

Cloudflare for Families uses 1.1.1.3 (malware blocking) or 1.1.1.2 (malware plus adult content blocking). It is free, requires zero account creation, and adds essentially no latency since Cloudflare’s network consistently posts sub-5ms response times in Ping tests from North American locations. The blocklist is maintained by Cloudflare and is not user-configurable. You get no logging, no per-device rules, and no way to see what is being blocked. It is a blunt instrument.

NextDNS is more sophisticated. The free tier allows 300,000 queries per month, and the paid tier runs $19.90 per year. NextDNS lets you choose from dozens of curated blocklists, set per-device profiles, log queries with retention options you control, and configure allowlist/denylist overrides through a web dashboard. Published comparisons from sites like Technitium and various homelab communities consistently put NextDNS’s configurable blocklists in the same range as Pi-hole when using equivalent list sources. The key limitation is that your filtering depends on NextDNS’s infrastructure. If their service goes down, DNS resolution on your network fails unless you configure a fallback resolver.

Some routers, particularly Firewalla devices and Eero Pro models with the Eero Plus subscription, build DNS-based threat filtering directly into the router firmware. Eero Plus costs $99 per year and uses a blocklist powered by the Eero security platform. Firewalla’s built-in IDS/IPS does deeper packet inspection in addition to DNS filtering. These are worth considering if you want protection without any external service dependency, though you are again trading configurability for simplicity.

For a deeper look at what router-level controls can and cannot do for families, see our router parental controls limitations guide.

Pi-hole: What It Runs On, What It Blocks, and What Falls Through

Pi-hole is free, open-source software that runs a local DNS server on your network. It was designed for Raspberry Pi hardware but runs on any Linux system including old laptops, Docker containers, a spare NAS, or a VM on a home server. The project’s GitHub shows active maintenance with regular releases, and the community around it is large enough that almost any configuration question has been asked and answered somewhere.

The core setup involves pointing your router’s DHCP server to hand out the Pi-hole’s IP address as the DNS server for every device on the network. Devices query Pi-hole first, Pi-hole checks the request against its blocklists, and forwards allowed queries to an upstream resolver of your choice.

Pi-hole ships with a default blocklist (StevenBlack’s unified hosts file) that covers roughly 100,000 domains. Most users add additional lists: the OISD blocklist covers about 200,000 domains in its full version, the HaGeZi Multi Pro list targets ads and tracking specifically, and specialized lists exist for malware, phishing, and regional ad networks. Running three or four well-maintained lists typically puts your active blocklist between 200,000 and 500,000 domains without significant false positive rates, based on community reports in the Pi-hole subreddit and forums.

What Pi-hole does not automatically handle: encrypted DNS bypasses (same problem as router-level filtering), apps that use hardcoded DNS servers like 8.8.8.8, and CNAME cloaking where trackers hide behind first-party CNAME records. Pi-hole added CNAME inspection in version 5.0 specifically to address that last issue.

Block Rate Differences: Why Pi-hole Catches More and When That Matters

The practical block rate advantage of Pi-hole over a service like Cloudflare for Families comes down to list volume and community responsiveness. Cloudflare’s blocklist is a black box with no public documentation of its size or update frequency. NextDNS closes that gap significantly because you can enable the same community-maintained lists that Pi-hole users run.

The real Pi-hole advantage is latency and query handling speed on local DNS resolution. Since Pi-hole runs on your LAN, cached responses resolve in under 1ms. NextDNS typically posts 5-20ms depending on your location and their nearest PoP. For most web browsing this is imperceptible, but for households with many IoT devices making frequent short DNS queries, local resolution reduces the chattiness noticeably.

Pi-hole also gives you a live query log that shows every DNS request from every device. This is where it gets genuinely useful beyond just blocking: you can see exactly which device is hammering ad networks at 3am, which app is phoning home every 30 seconds, and whether your smart TV’s DNS queries are going where you expect. No cloud-based filtering service gives you that level of visibility without sending your query data to their servers.

Maintenance Reality: Blocklist Updates, False Positives, and DNS Failures

This is where honest comparison matters most.

Pi-hole blocklist updates do not happen automatically by default in older versions, though Pi-hole v5 and newer supports scheduled gravity updates via cron. You still need to occasionally check that your lists are current, handle false positives manually (a site you need breaks because one of your lists incorrectly blocks it), and keep the underlying OS patched. On a Raspberry Pi 4, this is not a heavy burden, but it is not zero either. A realistic estimate is 30-60 minutes per month for a well-tuned setup, dropping significantly after the first few months once you have addressed your household’s specific false positives.

The failure mode for Pi-hole is also worth understanding. If the device running Pi-hole goes offline, all DNS on your network stops unless you have configured a secondary DNS server or set a fallback. A single-Pi-hole setup with no fallback will break internet access for every device on your network the moment the Raspberry Pi crashes, loses power, or needs to reboot for an update. Adding a secondary Pi-hole instance or a fallback resolver address in your DHCP config solves this but adds another layer to maintain.

NextDNS and Cloudflare for Families fail differently: if their service degrades, you either lose filtering but keep connectivity (if you have a fallback) or lose DNS entirely. Both services publish uptime statistics, and Cloudflare’s infrastructure in particular posts 99.99%+ uptime historically. But you have no control over that.

Which Setup Is Right Based on Your Tolerance for Maintenance

If you want something you configure once and largely forget: point your router at NextDNS with a few well-chosen blocklists enabled. Spend an hour setting it up properly, configure per-device profiles for kids’ devices, and revisit it when something breaks. The $19.90 per year is worth it over Cloudflare for Families purely for the visibility and configurability.

If you want maximum block rates, full query logging, and do not mind spending a few hours on initial setup plus occasional maintenance: Pi-hole on a Raspberry Pi 4 (which costs around $55 for the board alone) is the better choice. The community is large, the documentation is thorough, and the control you get over your own DNS infrastructure is genuinely useful for anyone running a more complex home network.

For families trying to enforce content restrictions on kids’ devices specifically, note that DNS filtering of any kind is not a complete parental control solution. A determined kid with a phone on cellular data bypasses your entire home network. See our home network VLAN guide for how network segmentation fits into a broader strategy.

Hybrid Approach: Pi-hole Upstream with Encrypted DNS

The setup that addresses the most failure modes combines both approaches. Pi-hole handles local DNS resolution and blocklist filtering. Upstream from Pi-hole, you configure encrypted DNS using either DNS-over-TLS (DoT) via Unbound as a recursive resolver, or DNS-over-HTTPS pointing to a trusted resolver. This prevents your ISP from seeing your upstream queries while keeping filtering local.

To handle the DoH bypass problem, you block outbound port 443 traffic to known DoH resolver IPs at your router’s firewall level. This forces devices that try to use DoH to fall back to your Pi-hole. It is not a perfect solution since new DoH IPs emerge regularly, but it catches the major browsers and most apps.

This hybrid configuration is more involved to set up than either approach alone. The Pi-hole community maintains detailed documentation for the Pi-hole plus Unbound configuration specifically. If you are already comfortable with basic Linux administration and your router has a firewall rules interface, the setup takes an afternoon and significantly tightens what DNS traffic actually reaches the public internet from your network.

The bottom line: router-only DNS filtering is fast to deploy and requires almost no maintenance. Pi-hole blocks more, shows you more, and gives you control that no cloud service can match. Pick based on how much that control is worth to you in time and attention.