Can I Block Multiple Domains & Keywords using my Router?

Do not use the built-in "Keyword Filter" on your router; it fails on 99% of modern websites because of HTTPS encryption.
Instead, configure your router to use a Smart DNS service like NextDNS or OpenDNS. This blocks domains at the network level before they even load.

In 2026, the entire web is encrypted (HTTPS/TLS 1.3).
Old routers could read the URL (e.g., `http://example.com/bad-keyword`).
Modern routers only see the handshake with `example.com`. They cannot see what comes after the slash. Therefore, blocking the word "game" in your router settings will not block `https://google.com/search?q=game`.
To block content effectively, you must control the "Phone Book" of the internet (DNS).

Checklist

• Access: Admin login to your router (usually `192.168.1.1` or `192.168.0.1`).
  
• Service: A free account on NextDNS.io or OpenDNS.
  
• The Hidden Requirement: DHCP vs. WAN DNS. If you use a locked ISP router, you cannot change the "WAN DNS." You must find the "LAN" or "DHCP Server" settings and change the DNS there. This forces devices to take the new DNS when they connect to Wi-Fi.
  

Step-by-Step Guide (The NextDNS Method)

• Step 1: Get Your Block List
  Go to NextDNS.io and create a free account.
  Go to the "Privacy" tab and add "OISD" (a comprehensive blocklist).
  Go to the "Parental Control" tab and add specific categories (Pornography, Gambling) or specific apps (TikTok, PUBG).
  Copy the IPv4 addresses listed on your Setup page (e.g., `45.90.28.xx`).
  
• Step 2: Router Configuration
  Login to your router.
  Navigate to Advanced > Network > LAN Settings (or DHCP Server).
  Look for "Primary DNS" and "Secondary DNS."
  Replace the existing values (often `0.0.0.0` or `8.8.8.8`) with the NextDNS IPs you copied in Step 1.
  
• Step 3: Link Your IP
  Since you likely have a Dynamic IP from your ISP, NextDNS needs to know who you are.
  In the NextDNS dashboard, click "Link IP".
  Pro Tip: You can set up a "DDNS" (Dynamic DNS) hostname in your router settings and add that hostname to NextDNS for auto-updating.
  

How It Works & Hidden Details
The DNS Sinkhole:
When a user on your Wi-Fi tries to visit `bad-site(dot)com`, their computer asks the Router: "Where is bad-site(dot)com?"
The Router asks NextDNS.
NextDNS checks your blocklist. If the site is allowed, it returns the real IP. If blocked, it returns `0.0.0.0` (Nowhere).
The user's browser simply displays "This site can't be reached." The connection is killed before any data is downloaded.

Things to Watch Out For

• Risk 1: Private DNS (DoH) Bypass. Android 10+ and Chrome browsers have a setting called "Secure DNS" or "Private DNS." If a user enables this on their device, they bypass your router's DNS entirely. You must block the domain `dns.google` and `cloudflare-dns.com` in your NextDNS blacklist to force devices to downgrade to your rules.
  
• Risk 2: Hardcoded DNS. Some smart devices (Chromecast/Roku) are hardcoded to use Google DNS (`8.8.8.8`). To block these, you need a high-end router (MikroTik/Ubiquiti) with NAT masquerade rules to intercept port 53 traffic.
  

Frequently Asked Questions

• Q: Can I block YouTube specific keywords?
  A: No. You can enforce "YouTube Restricted Mode" via DNS, but you cannot block specific search terms like "Fortnite" while allowing "Minecraft."
  
• Q: Will this slow down my internet?
  A: No. NextDNS has servers in Mumbai and Chennai. It is often faster than ISP default DNS.
  

Update: Additional Details & Recent Changes

• The IPv6 Leak (Critical):
  Most modern routers (especially ISP-provided ones) have IPv6 enabled by default. Even if you change the IPv4 DNS to NextDNS, your phone/PC will likely prefer the ISP's IPv6 DNS (via SLAAC/RA), bypassing your block entirely.
  Fix: You must either Disable IPv6 completely in your router's WAN/LAN settings OR enter the specific NextDNS IPv6 addresses (`2a07:a8c0...`) in the IPv6 DNS fields if available.
• Blocking "Private DNS" on Android (Port 853):
  Newer Android devices use "Private DNS" (DNS-over-TLS) which ignores your router's standard DNS settings. Simply blocking the domain `dns.google` is often not enough.
  Hard Fix: In your router's Firewall/Access Control settings, block TCP/UDP Port 853 for all LAN clients. This forces Android devices to fail the encrypted connection and fall back to your router's standard (filtered) DNS.
• NextDNS Free Tier Limits:
  Be aware that the free plan caps at 300,000 queries/month. On a busy home network with 4-5 devices, this runs out in about 20 days. Once the limit is hit, NextDNS stops blocking (it effectively becomes a standard non-filtering DNS), and all your restrictions disappear until the next month. Keep an eye on the analytics tab.
• Browser "Secure DNS" (DoH) Bypass:
  Chrome and Edge now default to "Secure DNS" (DNS-over-HTTPS). To prevent them from bypassing your router, add the canary domain `use-application-dns.net` to your NextDNS "Denylist." This signals compliant browsers (like Firefox) to disable DoH and use the system (router) DNS. For Chrome, you may need to block specific DoH domains (`mozilla.cloudflare-dns.com`, `dns.google`) in your blocklist.

To block these, you need a high-end router (MikroTik/Ubiquiti) with NAT masquerade rules to intercept port 53 traffic.

Update: This is technically called DNS Redirection or NAT Hijacking. While high-end gear is best, many consumer Asus routers (running Merlin firmware) now support "DNS Director" which performs this same interception easily without complex coding.