Connection error to FritzBox

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1

Expected Behaviour:

"No error to fritzbox. I use Unbound on 127.0.0.1#5335 and 192.168.178.1 for reverse lookup of hostnames (conditional forwarding). Pihole is in Fritzbox under Internet-DNS and as local DNS for ipv4 and ipv6.

Actual Behaviour:

Now I get the following error in pihole:
Connection error (192.168.178.1#53): TCP connection failed while receiving payload length from upstream (Connection prematurely closed by remote server)

I understood, that there is some kind of error related to unbound, but in my issue the IP ist my Fitzbox.

Debug Token:

https://tricorder.pi-hole.net/gTir7Se3/

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2

This would close a partial DNS loop if Pi-hole's Conditional Forwarding is turned on at the same time, which your debug log shows to be the case.

Remove Pi-hole from your Fritzbox's upstream DNS servers (Internet | Account Information | DNS server).

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Hi, thanks for you post. Generally understood. But for my curiosity.. Having a DNS loop I understood is when PiHole and Fritzbox have the same DNS upstream. If Pihole would use Fritzbox as upstream und Fritzbox Pihole as upstream. Am I wrong here? My Pihole uses Unbound as upstream and Fritzbox Pihole. And I don`t get the link to conditional forwarding.

2nd question: I am not 100% sure about the purpose of the DNS settings under Internet | Account Information | DNS server. If I would use here Quad9 my "fear" would be that the devices in my network would use Quad9 instead of Pihole.

By the way.. since I deactivated conditional forwarding I got no error - but now I get the same error but related to unbound as already written here in other posts..

Thanks!

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Internet | Account Information | DNS server defines where your Fritzbox to send its DNS requests.

By default, your FB will tell its clients to use the FB for DNS, and thus, all your clients DNS requests will ultimately be forwarded to those DNS servers, minus the few queries the FB can itself, i.e. for local names like fritz.box.

Since you've configured your Fritzbox to instruct its clients to use your Pi-hole machine's IP for DNS, your FB won't receive any DNS requests from your home network, only using its upstream DNS servers for its own requests (like firmware updates) and for its guest network (if that's enabled).

If you enable Conditional Forwarding to your FB, your Pi-hole will query your FB for local names. Your FB will answer them if it knows them, but if it doesn't, it forward them upstream. If that's Pi-hole, Pi-hole would then conditionally forward them to your FB, closing the partial DNS loop.

As for "failed to send TCP(read_write) packet (Connection prematurely closed by remote server)" messages triggered by unbound, see TCP connection failed while receiving payload length from upstream - #2 by Bucking_Horn.

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Thank you very much for your help. My last problem would be that:

Can’t delete PiHole diagnosis messages properly - #2 by hg1978

:slight_smile:

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