Custom DNS not working

[inwerds]

Hello - 

I am using the AC2200/2nd-gen Google Nest WiFi devices (3-pack).

Setup: www/internet -> modem -> Nest router/wifi -> LAN devices

On the Nest, I've configured Custom DNS per this article. It doesn't appear that any DNS traffic is hitting my specified DNS servers (I have logging enabled on these publicly accessible servers and don't see any traffic from the router's WAN IP address). I've changed DNS from Custom to Automatic and back again. I've also rebooted the entire Nest system, but I've still had no luck. 

Besides factory resetting my devices, what else can I do to force the Custom DNS settings?

Thanks!

[MichaelP]

Hello @inwerds 

I run my own DNS servers inside my network (a pair of Raspberry Pi units running "cloudflared" to tunnel all DNS traffic back out using DNS-over-HTTPS), and have my Google WiFi DNS configured to point to them. That definitely works – I get a lot of DNS traffic on them.

I have to wonder if your ISP is filtering DNS requests or something? You might try using the "dig" tool or some other DNS client that you can point directly at your DNS servers to test them from inside your network to verify it can even work at all.

[inewe]

Hello @MichaelP - thank you for the reply.  Running dig from a device inside the network and pointing it to the DNS server (94.140.14.49) that I have configured as the Primary Server on the Nest yields the results I would expect (it resolves):

;; Query time: 29 msec
;; SERVER: 94.140.14.49#53(94.140.14.49)
;; WHEN: Tue Oct 22 20:06:47 EDT 2024
;; MSG SIZE  rcvd: 100

Any other ideas?

[MichaelP]

Ok, that's good to know. You said earlier you had logging enabled on the DNS server – did you see your test requests get logged? If not, you may have a double-NAT situation going on, which means the WAN IP address you have isn't the actual public IP address your traffic is using on the internet.