Use DNS servers advertised by peer selected low score on


If I select Use DNS servers advertised by peer, I get a 9/10 score from website. But if I manually add my ISP's DNS servers I get 10/10. I'm using PPPOE also using the latest x86 stable.

It's no biggie as I can manually add the DNS servers, I just thought of reporting it.

What test failed?

What did your ISP suggest when you reported it?

(For some reason, imgur screenshots always appear fuzzy to me - apologies if your pic shows it.)


The error message from the site's source code is basically self-explanatory:


My ISP says everything is good on their end.

I also use Opnsense and I get 10/10 when I select DNS by Peer.

As for fuzzy are you using a PC or a mobile device? With mobile devices they tend to go fuzzy.

Collect the output when the issue happens:

sed -n -e "/^nameserver\s/s///p" /tmp/resolv.* /tmp/resolv.*/* \
| sort -u | while read -r DNS; do nslookup ${DNS}; done
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This is what I get:

I never had this problem with version 19 only with 22 release. I should of probably reported it earlier, but meh better late than never. Plus I thought someone else might report it and was hoping it would be ironed out.

Anyways I'm just reporting, no biggie as I can happily add the ISP DNS servers manually.


Just curious, when you say this, do you mean to OpenWrt or your ISP?

just saying what my router is experiencing. For the lack of a better word

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I figured it out! It was my MTU set at 1488, but once I set it to 1492 it's 10/10. Woo hoo!

Thank you to all the guys who tried to help, much appreciated.

Bye :smiley:



  • Neither of those are the default (additionally, 1492 seems like you edited it for PPPoE :man_shrugging: ); and
  • It's never mentioned in the thread

FYI, if you're not running PPPoE - standard Ethernet MTU is 1500. Nonetheless, glad you got it working!

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Even with PPPoE OpenWrt defaults to MSS clamping, so one does not need to manually adjust the MTU generally...


Your DNS seem to work correctly resolving the domain name to IPv4 and IPv6.
But the configured DNS are limited to IPv4, so your IPv6 setup cannot operate independently.

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That make sense!


It seems the developer was smart enough to use DNS tests that would test the length of the packet and if it was fragmented. This could be done using the domains and counting the bytes.*

A lot of DNS tests use random, low [DNS] TTL set domains for various tests.

Wow, that's cool!

*-Before I had native IPv6, it used to give me a notice that one of my IPv (either 4 ot 6) was tunneled. I won't get into details,but my guess was MTU. The other was IP lists that mark as being datacenters/VPNs

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Actually, there's even better explanation for the discussed issue.
I have not discovered any relation to MTU other than potentially EDNS(0).
Assuming OpenWrt is up to date, it should not cause any problems:

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