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DNS failing to connect to free servers

peteispo
Team Player
Message 5 of 5

I've got a HG633 router, and a Raspberry PI running PiHole for Ad blocking, so the DCHP settings on the HG633 are setting DNS for LAN clients to the PiHole, and the PiHole is using a combination of Google, Cloudflare and OpenDNS to forward DNS requests to. To be clear, I'm NOT using TalkTalk DNS servers at all in this configuration.
Anyway, at least once a day I'm getting all DNS queries blocked somewhere outside of my LAN. The PiHole is logging the requests and not receiving a response. After a while it goes away and DNS requests are successful for a bit. Usually a router restart clears the problem but that's not exactly convenient with a house full of people working from home and gaming on-line...

What I don't understand is why this even happens - what would be blocking DNS requests to three major public DNS services? And why would it be so intermittent?
The conspiracy theory says that TalkTalk are filtering DNS requests for some reason, but that would not explain the intermittent behaviour.
One thing that is for sure, the ADSL connection is not being dropped - anything that knows the IP address it needs stays connected (like VPN connections, and Minecraft servers as far as I can tell from the room next door). It is *only* DNS that seems to be a problem.

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4 REPLIES 4

Message 1 of 5

Wireshark? I'm not quite ready for the Nuclear option...
As it happens I have a second shiny new HG633 lying around, so I tried copying the config from the existing one to the new one. It looks like there's something corrupt in the config because it wouldn't accept the config file.
So I found an older config backup from last year and tried that. It seems to work so I'll see if the older config plus new router fixes the issues.

Otherwise I'll be digging out the Wireshark manual...

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KeithFrench
Community Star
Message 2 of 5

In that case, I would think the only way forward is to find out the exact cause by taking Wireshark traces.

Keith
I am not employed by TalkTalk, I'm just a customer. If my post has fixed the issue, please set Accept as Solution from the 3 dot menu.
TalkTalk support and Community Stars - Who are they? 

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Message 3 of 5

Keith,

With respect, my (long-winded) original post makes that fairly clear: I'm finding that Google and OpenDNS are failing too.
Having dug around in the PiHole logs, it looks like Cloudflare (or at least their 1.0.0.1 server) is returning results more consistently, so I've dropped Google and OpenDNS out of the mix for now and we'll see how it goes.

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KeithFrench
Community Star
Message 4 of 5

Have you set the router's DNS server to something like Google DNS? On the HG633 to do this go to:-

 

Internet > Internet Connection > Edit

 

Then scroll down to the "IP Information" section & put a tick against "Static DNS". This expands to allow you to choose what ones to use.

 

 

Keith
I am not employed by TalkTalk, I'm just a customer. If my post has fixed the issue, please set Accept as Solution from the 3 dot menu.
TalkTalk support and Community Stars - Who are they? 

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