Apple’s AirDrop makes weird latency spikes for Wi-Fi wonks, researcher finds
- Reference: 1761197048
- News link: https://www.theregister.co.uk/2025/10/23/apple_airdrop_awdl_latency_research/
- Source link:
Visser presented his findings on Tuesday at the RIPE 91 conference, the biannual internetworking event organized by RIPE NCC, the regional internet registry for Europe, the Middle East and parts of Central Asia. In his [1]talk , titled “Apple Wireless Direct Link: Apple's Network Magic or Misery,” Visser explained that while using a new iPad he often encountered what he described as “very strange rhythmic stuttering” as he streamed audio to the device.
He used the Moonlight [2]streaming test tool to investigate and found 20 millisecond latency, but with a 25 millisecond variance he felt was oddly high for the uncontested environment that is a local network. He next used Steam’s network testing tool, and found latency regularly bounced between three and 90 milliseconds. PING commands produced similar results, as did tests on different devices.
[3]
At this point, Visser felt confident his hardware and applications were not the reason for his streams stuttering.
[4]
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Visser, who works at Japan’s IIJ Research Lab, dug into the situation and found AWDL constantly listens for requests to use AirDrop, and prefers to use certain “social” Wi-Fi channels - channel 6 for 2.4 GHz networks channels 44 and 149 for 5 GHz Wi-Fi.
As a networking engineer, Visser chose to use empty channels.
[6]
“It’s a big mistake,” he told the conference. “What ends up happening is that if you are not in one of these social channels, you get this periodic Wi-Fi channel swapping where it goes to the social channel, listens in [if] anybody wants to talk to it and swaps back to create very rhythmic stuttering.”
[7]Australian university used Wi-Fi location data to identify student protestors
[8]Apple goes all in on AI acceleration with M5 MacBook, iPad, and Vision Pros
[9]Dutch teen duo arrested over alleged 'Wi-Fi sniffing' for Russia
[10]Who gets a Mac at work? Here's how companies decide
Visser suggested one way to avoid the issue is not to use AWDL but acknowledged that doing so means users of Apple devices will have to do without AirDrop and other Cupertino tricks like using an iPad as an external monitor for a Mac or mirroring an iPhone screen.
He doesn’t think cutting users off from those services is practical.
“There's approximately over 1.5 billion other iPhone users in the world and are you really going to tell your users in your network ‘Don't use the features on these Apple devices’. It's not really a solution.
“The other option is to do the Apple way of networking, so for the best experience you use the same Wi-Fi channels as everybody else, or you will suffer from jitter at some point.”
[11]
He ended his talk by expressing his concerns about Apple’s ecosystem.
“There's a lot of convenience, as I described,” he said. “The question is really: Is this convenience worth disruption?”
His answer was “For most things sure, it doesn't matter too much.”
But he feels it will matter to more people in future.
“Cloud gaming and remote gaming is growing bigger and bigger and they are trying to push high fidelity, bigger bit rate, if you are trying to do 4k HDR at 120 FPS, yes you are going to start to feel these delays and packet loss more and more.”
“It makes me uncomfortable because it really promotes bad network practices like not using the best channels to actually improve your end user experience,” he added.
He therefore grudgingly recommended using the Wi-Fi channels Apple uses, and expressed his hope that any folks from ISPs in the audience can learn from his experience so that if their customers experience network jitters they now have an explanation. ®
Get our [12]Tech Resources
[1] https://ripe91.ripe.net/programme/meeting-plan/sessions/15/3KJJLU/
[2] https://github.com/moonlight-stream
[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/networks&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2aPn8te8BfUWXkmjapjUH3wAAAUk&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/networks&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44aPn8te8BfUWXkmjapjUH3wAAAUk&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[5] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/networks&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33aPn8te8BfUWXkmjapjUH3wAAAUk&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[6] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/networks&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44aPn8te8BfUWXkmjapjUH3wAAAUk&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[7] https://www.theregister.com/2025/08/25/asia_tech_news_in_brief/
[8] https://www.theregister.com/2025/10/15/apple_goes_all_in_on/
[9] https://www.theregister.com/2025/09/29/infosec_in_brief/
[10] https://www.theregister.com/2025/10/11/who_gets_mac_at_work/
[11] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/networks&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33aPn8te8BfUWXkmjapjUH3wAAAUk&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[12] https://whitepapers.theregister.com/
Re: Do As I Say
"you're just holding your WiFi network wrong."
FTFY
Re: Do As I Say
Does anyone ever use AirDrop? I've tried it a couple of times to move stuff between my machines and it's always been more faff, slower and less successful than anything else.
"do the Apple way of networking"
It's the Apple way, or the highway.
Not using Apple is recommended, but not spoken of.
On the other hand, this is one case of very good naming on Apple's side.
Re: "do the Apple way of networking"
I chose the highway. I only have one ten year old Macbook Air, and that's running Linux. (that does speak positive to apple's hardware, however)
This should be brought to the attention of the Wi-Fi Alliance since they are responsible for certification of Wi-Fi devices. Apple has representatives there who should be expected to explain themselves.
From reality distorsion field...
.... to WiFi distortion field.
Apple engineers have a very strange idea of WiFi - there are multipe channels for a good reason, and there are advanced APs that can change channel dinamically to work on the less crowded one.
Also, on 2.4Ghz using the channel "everybody else" use is even worse.
This sounds like a bug, AWDL uses Bluetooth Low Energy (BLE) for discovery and only switches to Wifi when a connection is requested (such as a file being airdropped) so it shouldn't be switching wifi channels unless it is being used.
Its an even bigger bug that the transfer can only happen on wifi and not on a wired connection. Took me a while to figure out why airdrop stopped working when I was on a wired connection with wifi turned off. IP is IP, doesn't matter what physical medium it travels over.
That's not really a bug, just a missing feature/odd design decision.
Airdrop is a P2P connection using Apple Wireless Direct Link (AWDL), so it sets up a direct connection from a virtual network interface on the wifi modem (and on bluetooth). It doesn't use your actual network connection, but essentially a modified WiFi Direct connection.
I find this quite odd, considering AirPlay does work using both AWDL and regular networking (mDNS discovery, if i'm not mistaken).
It is an advantage that you don't need to be on the same network, but having the option to use your regular network would be a huge improvement.
More information can be found on the [1]Open Wireless Link (OWL) Wiki , they reverse-engineered the AWDL protocol. In the table, the AP column also includes ethernet links if i'm not mistaken.
[1] https://owlink.org/wiki/
Unprecedented
Apple not giving a damn about the user's preferences, networks or other devices and just doing what they damn well want.
Unprecedented.
I miss the obvious first step in this article..
.. has anyone actually informed Apple (or at least tried to)?
For me that is a logical first step - if you find something that doesn't sit well with business infrastructure, go talk to the provider. I see no report of even an attempt at communication with Apple which, when not succesful, would then give rise to publication. I call that responsible discovery, akin to responsible disclosure.
Re: I miss the obvious first step in this article..
Putting your findings on the internet IS informing Apple in the best way possible. Apple's PR department finding out about a bug that harms their image will get the issue addressed far sooner than an easily ignored quiet word to the engineering department that hasn't been allocated sufficient budget to test for bugs.
Do As I Say
Although this isn't and probably won't be an issue for a lot of the users of the Apple ecosystem right now, this is another example of where a vendor has decided that 'they know best' and are deliberately ignoring a users own preferences, causing an unnecessary issue and making the user experience worse. Mind you, Apple will say this isn't their fault, you've just configured your WiFi network wrong.