Dumb AP w/ Guest WiFi - How To Route DNS Traffic to Pihole

Installing and Using OpenWrt Network and Wireless Configuration
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Hi All,

New OpenWRT user and networking neophyte in general. I followed the guide to get the Dumb AP w/ Guest Wifi working, and it's working great. Thanks to the contributors. My next challenge is that I want a Pihole to handle DNS queries.

My environment:

  • 192.168.0.1: ATT LTE modem/router/wifi device. This is the gateway and its LAN DHCP cannot be disabled, nor can a custom DNS server be specified. The firmware has VERY few options; great modem, crappy router. LAN jack connects to an unmanaged switch which feeds LAN clients and the Dumb AP below.
  • 192.168.0.3: Pihole with Unbound
  • Archer A7 running OpenWRT as a Dumb AP w/ guest WiFi, configured per the aforementioned instructions. The br-lan interface (bridged lan and 2.4/5 wireless) is running as a DHCP client and gets leases from 192.168.0.1. The guest interface (bridged guest wireless 2.4/5) is running a DHCP server on 192.168.1.2.

I've read a number of threads from around the web but best I've been able to achieve is specifying the pihole's IP in the guest interface as a custom DNS server, and manually setting the pihole's IP on other non-guest clients. Obviously, this does nothing for the br-lan interface, nor does it force DNS queries to be routed to the pihole. No port forwards or NAT rules I've tried have worked but, admittedly, I have very limited knowledge.

In terms of forcing all DNS queries to the pihole, since the gateway is handling the routing for all the hardwired clients, I'm wondering if the best I could achieve is forcing all Dumb AP wireless client DNS queries to the pihole.

Big picture, an alternate physical configuration is that I could have the gateway LAN directly feed the Dumb AP, then have the Dumb AP feed the switch and other LAN clients.

I'm mainly interested in if what I want to do is possible and, if so, how to accomplish it. Can post config files as necessary, just didn't want to clog the first post since this is more of an "is this possible" question at this point.

Thanks in advance!

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Since you're using LTE, double NATing shouldn't really have a major impact on your speed.
I'd run a 2nd NAT (connect ATT LTE -> WAN on A7) on the A7, which would give you full control of the network.

Don't forget to put the A7 LAN on a diff subnet than the ATT LTE.

2 Likes
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Thanks for the advice. I thought I may have been missing something obvious since I've always heard that double NAT was to be avoided. I guess this is a case where avoidance isn't possible.

I've configured it as suggested and things are working great now, with no performance issues even when online gaming.

Thanks again for the assistance!

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