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iOS 26 / 26.0.1 - No or slow DNS on cellular

Hello,

after I installed iOS 26 on my iPhone 14 Pro, DNS requests for installed NextDNS app in mobile became extremely slow or broke off with timeout. Uninstalling of the app and setting up a NextDNS profile also did not solve the problem.
There were no problems in the WLAN.
Also, a reset of the network settings and a restart of the mobile phone did not bring a solution.

Even after switching to an iPhone 17 Pro, the problem was reproducible. With other DNS profiles, e.g. Mullvad, it works without problems.
Even use without private relay has not brought any improvement.
iOS 26.0.1 also not.

I tested all this in the network of Deutsche Telekom and Vodafone. To my knowledge, both networks rely entirely on IPv6.
My landline is also natively IPv6, but the problem does not occur in the WLAN via it.

The issue does not occur on an iPhone 13 Pro with iOS 18.x.

Is anything known that Apple has changed anything in the current versions that can trigger this behavior? And if so, how can I solve the problem?

Greeting
Wutti

39 replies

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    • wutti
    • 4 days ago
    • Reported - view

    Sorry, but I don't use NextDNS any more. Other services can handle IPv6 and Private Relay without problems and so I switch completely.

    But many thanks for your support and the tests. Hope that will help other users with similar problems in the future 🙂

      • Martin.30
      • 3 days ago
      • Reported - view

       
      could you elaborate on this a bit more ?
      which provider do you use now and do you use it with a profile ?

      • wutti
      • 3 days ago
      • Reported - view

       switched from NextDNS to AdGuard DNS and there are no problems with iOS26.x, Private Relay and IPv6

      • wutti
      • 2 days ago
      • Reported - view

       Phone Provider is the same as before. Telekom and Vodafone

    • Martin.30
    • 2 days ago
    • Reported - view

    but to get you correctly - since you switched you do not have the page loading delay any more ?

    So with an encrypted DNS profile installed on iOS the pages are loading instantly ?

      • wutti
      • yesterday
      • Reported - view

       that's right.

      • Private Relay activated
      • AdGuard DNS DoH Profile installed and active
      • No Problems with Cellular (Telekom, Vodafone)
      • No Problems with Wifi
      • Martin.30
      • yesterday
      • Reported - view

       That's crazy...
      tried it myself and problems seem to be gone.
      (But: iCloud private relay is disabled and will be re-enabled when available again)
       

      ControlD was no help either...

      Asking myself where the difference may be ...

      • Martin.30
      • yesterday
      • Reported - view

       
      unchecked the box and private relay works 🙂

      • wutti
      • yesterday
      • Reported - view

       reactivated my NextDNS on my iPhone. Same as before.

      On WiFi (IPv6 internet connection) there are no problems.

      After switching to cellular (IPv6 internet connection) the first website loading needs up to 2 Minutes. The next sites are loading with normal speed.

      That‘s very curious. 

      All tested with active Private Relay. 

      What box did you unchecked?

      • Martin.30
      • yesterday
      • Reported - view

       I have the problem here that after a "cool down time" of the iPhone and safari the problem arises with every encrypted DNS provider.
      I now tested NextDNS, ControlD, AdGuard and other free providers (HaGeZi, dnsforge, DNS4EU) and the problem persists with every single provider...

      So it might either be a problem with safari (because in the DNS-provider logs I see the traffic from the device itself immediately (App-Store, ...) even while safari "loads".
      Or it might be a problem with the ISP (what makes no sense because of the logs that show immediately traffic).

      In AdGuard i unchecked the box "Zugriff auf iCloud Private Relay blockieren" from Server -> Default -> Erweitert

      • wutti
      • yesterday
      • Reported - view

       ok, this box is deactivated in my AdGuard config. I tried something new... In the Safari Settings I switched the config "IP-Adresse verbergen" from "Tracker und Websites" to "Nur Tracker" and now the website loading after switching to cellular war normal fast.

      Can you test and verify this?

      • wutti
      • yesterday
      • Reported - view

       That should be no problem with privacy because with IPv6 the address should switch after every switch to cellular.

      In Wifi there is the option to rotate the Mac address.

      • Martin.30
      • yesterday
      • Reported - view

        That makes no difference here - loading times stay slow.

      • wutti
      • 23 hrs ago
      • Reported - view

       ok, that's spooky

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