Fix: Pi-hole Not Blocking Ads On VLAN? Easy Guide

Hey guys! Ever found yourself pulling your hair out because your Pi-hole just isn't blocking ads and trackers on certain VLANs? You're not alone! This is a super common issue, and thankfully, it's usually fixable. Let's dive into some troubleshooting steps to get your Pi-hole working across all your VLANs like a champ.

Understanding the Problem: Why Isn't Pi-hole Blocking VLAN Traffic?

So, you've got your Pi-hole set up, and it's doing a fantastic job blocking unwanted content on your main network. But when you switch over to a different VLAN, suddenly the ads are back, and your trackers are running wild. What gives? The issue often boils down to network configuration and how your VLANs are interacting with your Pi-hole. Let's explore the common culprits:

• DNS Server Assignments: This is the big one. Your devices on the problematic VLAN might not be using your Pi-hole as their DNS server. They might be defaulting to your router, your ISP's DNS, or even public DNS servers like Google's (8.8.8.8) or Cloudflare's (1.1.1.1). If your devices aren't querying Pi-hole, it can't block anything!
• Firewall Rules: Your firewall might be blocking DNS traffic (port 53) from your VLAN to your Pi-hole. Firewalls are designed to control network traffic, and if a rule is in place that prevents communication between your VLAN and your Pi-hole, you'll run into issues.
• VLAN Routing: Sometimes, the routing between your VLANs isn't set up correctly. This means that traffic from your VLAN might not be able to reach your Pi-hole's IP address. Think of it like trying to send a letter to a friend who lives on a different street, but the post office doesn't know how to get there. Proper routing ensures that your network traffic can flow correctly.
• Pi-hole Configuration: There's also a chance that Pi-hole itself isn't configured to listen on the correct interfaces or isn't aware of your VLANs. Pi-hole needs to know which network interfaces to monitor for DNS requests.
• DHCP Server Settings: Your DHCP server (usually your router) is responsible for assigning IP addresses and other network information to devices. If the DHCP server for your VLAN isn't configured to hand out your Pi-hole's IP address as the DNS server, your devices won't use it.

Step-by-Step Troubleshooting: Getting Pi-hole to Block on All VLANs

Alright, let's get our hands dirty and start fixing this! We'll go through a series of steps to identify the problem and get your Pi-hole blocking those pesky ads on all your VLANs.

1. Verify DNS Server Assignments on Your VLAN

This is the most crucial step. We need to make sure your devices on the VLAN are actually using Pi-hole for DNS. Here's how you can check:

• On your computer:
  • Windows: Open Command Prompt and type ipconfig /all. Look for the "DNS Servers" entry for your network adapter. It should list your Pi-hole's IP address.
  • macOS: Open Terminal and type networksetup -getdnsservers Wi-Fi (if you're on Wi-Fi) or networksetup -getdnsservers Ethernet (if you're wired). Again, you should see your Pi-hole's IP.
  • Linux: The method varies depending on your distribution, but you can usually find DNS server information in /etc/resolv.conf or by using the nmcli command.
• On your mobile devices:
  • Android: Go to Settings > Connections > Wi-Fi, tap the gear icon next to your Wi-Fi network, and look for "IP settings" or a similar option. You might need to switch from DHCP to Static IP to view the DNS servers.
  • iOS: Go to Settings > Wi-Fi, tap the "i" icon next to your network, and scroll down to the "DNS" section.

If you don't see your Pi-hole's IP address listed as a DNS server, that's a major clue! It means your devices are using a different DNS server, and Pi-hole isn't even in the picture. We'll fix this in the next steps.

2. Configure DHCP Server to Distribute Pi-hole's IP

Okay, so you've confirmed that your devices aren't using Pi-hole for DNS. Now, we need to tell your DHCP server (usually your router) to hand out your Pi-hole's IP address as the DNS server. Here's the general process:

1. Access your router's web interface. This usually involves typing your router's IP address into a web browser (e.g., 192.168.1.1, 192.168.0.1, or 10.0.1.1). You'll need your router's username and password.
2. Find the DHCP settings. The exact location varies depending on your router's make and model, but look for sections like "DHCP Server," "LAN Settings," or "Network Settings."
3. Specify Pi-hole's IP as the DNS server. You should see fields for "DNS Server 1" and "DNS Server 2." Enter your Pi-hole's IP address in "DNS Server 1." You can optionally enter a secondary DNS server (like 1.1.1.1 or 8.8.8.8) in "DNS Server 2" as a backup, but keep in mind that this will bypass Pi-hole if the primary DNS server is unavailable.
4. Save your changes and reboot your router. This ensures the new DHCP settings are applied.
5. Renew DHCP leases on your devices. On your computer, you can do this by opening Command Prompt (Windows) or Terminal (macOS/Linux) and typing ipconfig /renew (Windows) or dhclient -v (macOS/Linux). On mobile devices, you can usually disconnect and reconnect to your Wi-Fi network.

After these steps, re-check the DNS server assignments on your devices (as described in Step 1). You should now see your Pi-hole's IP address listed.

3. Check Firewall Rules

If you've configured your DHCP server correctly, but Pi-hole is still not blocking ads on your VLAN, your firewall might be the culprit. You need to ensure that your firewall isn't blocking DNS traffic (port 53) between your VLAN and your Pi-hole.

1. Access your router's web interface.
2. Find the firewall settings. Look for sections like "Firewall," "Security," or "Access Control."
3. Check for any rules that might be blocking DNS traffic. You might have a rule that specifically blocks traffic on port 53 or a more general rule that blocks traffic between your VLAN and your Pi-hole's IP address.
4. Create a rule to allow DNS traffic. If you find a blocking rule, you'll need to create a new rule that allows traffic on port 53 from your VLAN to your Pi-hole's IP address. The exact steps for creating a firewall rule will vary depending on your router.
5. Save your changes and reboot your router.

4. Verify VLAN Routing

If your VLANs aren't properly routed, traffic from one VLAN might not be able to reach devices on another VLAN, including your Pi-hole. This is especially common in more complex network setups.

1. Access your router's web interface.
2. Find the routing settings. Look for sections like "Routing," "Static Routes," or "Inter-VLAN Routing."
3. Ensure that there's a route allowing traffic from your VLAN to your Pi-hole's network. You might need to add a static route that specifies the destination network (your Pi-hole's network), the gateway (your router's IP address on the VLAN), and the interface (your VLAN's interface).

This step can be a bit more technical, and the specific configuration will depend on your router and network setup. If you're unsure, consult your router's documentation or seek help from a networking expert.

5. Configure Pi-hole to Listen on All Interfaces

By default, Pi-hole usually listens on all interfaces, but it's worth double-checking to make sure it's configured correctly.

1. Access your Pi-hole's web interface. Open a web browser and go to http://<your_pihole_ip>/admin.
2. Log in to the admin panel.
3. Go to Settings > Interface settings.
4. Make sure "Listen on all interfaces" is selected. If it's not, select it and save your changes.

6. Test DNS Resolution

After making any changes, it's a good idea to test if DNS resolution is working correctly. You can use the nslookup command in Command Prompt (Windows) or Terminal (macOS/Linux) to query a domain name.

nslookup google.com

If Pi-hole is working correctly, you should see your Pi-hole's IP address as the server and the IP addresses for google.com in the response. If you see a different DNS server or an error, something is still not configured correctly.

Advanced Troubleshooting Tips

If you've gone through all the above steps and you're still having issues, here are a few more advanced tips:

• Check Pi-hole's Query Log: The Pi-hole web interface has a Query Log that shows all DNS queries it has processed. This can help you see if requests from your VLAN are even reaching Pi-hole. If you don't see any queries from your VLAN, that indicates a routing or firewall issue.
• Use tcpdump to Capture Network Traffic: If you're comfortable with the command line, you can use tcpdump on your Pi-hole to capture network traffic and see exactly what's happening with DNS requests. This can be a powerful tool for diagnosing complex network issues.
• Temporarily Disable Firewall Rules: As a troubleshooting step, you can temporarily disable all firewall rules to see if that resolves the issue. If it does, you know the problem lies in your firewall configuration. Just remember to re-enable your firewall rules after testing!
• Consider DNS Masquerading: In some complex network setups, you might need to use DNS masquerading to ensure that DNS requests from your VLANs are properly routed to your Pi-hole. This involves configuring your router to rewrite the source IP address of DNS requests to the router's IP address.

Conclusion: Conquering VLAN Blocking with Pi-hole

Getting Pi-hole to work seamlessly across all your VLANs might seem daunting at first, but with a systematic approach and a little bit of troubleshooting, you can definitely get it done. Remember to double-check your DNS server assignments, firewall rules, and VLAN routing. And don't be afraid to dive into the Pi-hole Query Log or use network analysis tools like tcpdump if you need to dig deeper.

By following these steps, you'll be well on your way to enjoying a cleaner, ad-free browsing experience across your entire network! Good luck, and happy blocking!