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Timeouts and bad performance on NextDNS with IPv6

Hello,

I find myself getting more and more timeouts lately, the frequency increasing every day. When I don't get a timeout, it does still take ages for anything to happen. Some domains will consistently time out whenever I connect, and are unreachable.

I did find that the issue is exclusive to the combination of NextDNS and IPv6 – either disabling IPv6 or switching to a different DNS immediately makes the timeouts stop and drastically improves performance.

Here is my diag: https://nextdns.io/diag/d8978320-4a3e-11ee-833f-b5a30793dcb1

And, of course, some example domains that showcase the issues:

Until this gets fixed, I suppose I'll just have to disable IPv6 for a while as a workaround.

2 replies

null
    • Nition
    • 2 mths ago
    • Reported - view

    Same situation here. I'm based in New Zealand. IPV6 is incredibly slow - can take a good 10 seconds to resolve a website, although it doesn't usually time out completely. Disabling IPV6 resolves the issue and it becomes fast.

    • Jurriaan
    • 3 days ago
    • Reported - view

    Yes, same issue here, based in the Netherlands. Both primary and secondary DNS have a lot of timeouts like this:
     

    $ nslookup google.nl 2a07:a8c1::xx:xxxx
;; communications error to 2a07:a8c1::xx:xxxx#53: timed out
Server: 2a07:a8c1::xx:xxxx
Address: 2a07:a8c1::xx:xxxx#53

Non-authoritative answer:
Name: google.nl
Address: 142.251.36.35
;; communications error to 2a07:a8c1::xx:xxxx#53: timed out
;; communications error to 2a07:a8c1::xx:xxxx#53: timed out
Name: google.nl
Address: 2a00:1450:400e:810::2003

$ dig +tcp @2a07:a8c1::xx:xxxx google.nl
;; Connection to 2a07:a8c1::xx:xxxx#53(2a07:a8c1::xx:xxxx) for google.nl failed: timed out.
;; no servers could be reached

; <<>> DiG 9.20.7 <<>> +tcp @2a07:a8c1::xx:xxxx google.nl
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63615
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;google.nl. IN A

;; ANSWER SECTION:
google.nl. 300 IN A 142.251.36.35

;; Query time: 12 msec
;; SERVER: 2a07:a8c1::xx:xxxx#53(2a07:a8c1::xx:xxxx) (TCP)
;; WHEN: Fri Apr 11 14:13:00 CEST 2025
;; MSG SIZE  rcvd: 54
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