iPhone 13 Pro buffering and picture loading issues with DNS servers

Question

Level 1

23 points

iPhone 13 Pro buffering and picture loading issues with DNS servers

When using DNS servers like Cloud9, ControlD and AdGuard (a the router level), I get frequent buffering on my iPhone 13 Pro. Pictures fail to load on Facebook and Instagram apps, other apps may buffer when launching. Minutes later all works perfectly, but after a while it comes back. Seems random and it happens every day.

This only happens on the iPhone, it does not happen on PC. Is there any setting that can be causing this?

[Re-Titled by Moderator]

Original Title: DNS issues (buffering)

iPhone 13 Pro

Posted on Aug 18, 2025 2:31 AM

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Answer 1

Tech_42

Level 1

20 points

Aug 18, 2025 2:02 PM in response to David_27

I've had a similar problem occasionally with Cloudflare's dns. One time when I was bored, I fired up GRC's dns benchmark on my PC, and captured the results when my iPhone was acting up. Sure enough, when my iPhone was misbehaving, dns response times went thru the roof. I can only surmise that as DNS uses a UDP protocol, and it is NOT local to my ISP's network, that when traffic is heavy at their edge switches/routers my ISP is dropping UDP packets, in favor of TCP. I'm guessing that this is what you're experiencing, and no, there isn't anything you can do about it (other than using a "closer" DNS server).

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Answer 2

David_27 Author

Level 1

23 points

Aug 18, 2025 6:22 PM in response to Lawrence Finch

It's not a problem with the DNS servers, as all devices work perfectly fine except iPhones. I have a PC with a 9800X3D and a 5070 Ti that I've been using all day long and it never has any latency or any other kind of problem with my 1 Gbps connection.

Most experienced people know why you should use third party DNS servers and these are among the best.

I'm starting to suspect that the problem was the "Limit IP Address Tracking" setting on the iPhone. I will report soon if the problem is actually fixed.

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Answer 3

Aug 18, 2025 11:01 AM in response to David_27

Why are you using those DNS servers? It is clearly a problem with the servers, as it goes away if you don’t use a 3rd party DNS, so you should contact support for those servers.

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Answer 4

KiltedTim

Level 10

224,688 points

Aug 18, 2025 11:37 AM in response to David_27

Patient: Doctor, it really hurts when I bend my arm this way.

Doctor: Then don't bend your arm that way.

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