Triggering “realtime” mode for peer-to-peer WiFi via awdl to fix jitter problems

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Created 1w

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This is a bit complicated to explain so bare with me. I am working on building an app that allows you to send real time video/camera captures from one Apple device to another. I am using a custom UDP protocol built on top of NWListener, NWBrowser, and NWConnection APIs. It works fine, but there are a few issues that seems to all be related to awdl:

When transmitting via WiFi over the router (not using peer-to-peer), there are periodic interruptions when the wireless card on the device changes channels for awdl polling. This is resolved by changing the 5GHz WiFi channel on the router to channel 149 (or disabling AWDL altogether which is not really feasible).
In order to work around number 1, I decided to build in an option to toggle/prefer peer-to-peer transmission in the app thinking that if everything goes over a peer-to-peer connection the jitter caused from the channel switching should go away. This also works, but with an important caveat. The default transmission is extremely choppy until you take an OS action that “elevates” the AWDL connection into “realtime” mode. I am using includePeerToPeer on the listener, browser, and connection as well as serviceClass interactiveVideo.

For number 1, you can understand that asking users to change the channel on their router is not a great user experience, but the problem is the peer-to-peer connection workaround is also not great by default.

For number 2, as an example of the behavior, I can send a stream from my Mac to my iPad over a peer-to-peer connection and it works but the video is very choppy until I move my cursor from my Mac to my iPad to trigger Universal Control. I captured the OS logs while doing this and can confirm that something happens to trigger “realtime” mode on the AWDL connection. After that, the streaming is totally smooth with zero latency.

Some log samples:

2026-03-19 12:42:01.277968-0400 0x1ae294c  Default     0x0                  495    3    rapportd: (CoreUtils) [com.apple.rapport:CLinkD] Update client from UniversalControl:697
2026-03-19 12:42:01.278031-0400 0x1ae294c  Default     0x0                  495    0    rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Connect start: 'CLink-ed3b9618b4e0._companion-link._tcp.local.%13'
2026-03-19 12:42:01.278149-0400 0x1ae294c  Default     0x0                  495    0    rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Querying SRV CLink-ed3b9618b4e0._companion-link._tcp.local.%13

2026-03-19 12:42:01.279454-0400 0x1ae253a  Info        0x0                  382    0    wifip2pd: [com.apple.awdl:datapathInitiator] Created AWDLDatapathInitiator clink-ed3b9618b4e0._companion-link._tcp.local <To: 2e:f2:5a:15:76:52>
2026-03-19 12:42:01.279498-0400 0x1ae294c  Default     0x0                  495    0    rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Resolving DNS f970afcc-1f1c-47af-a3f3-0236c9f9bbb0.local.%13
2026-03-19 12:42:01.279588-0400 0x1ae253a  Default     0x0                  382    0    wifip2pd: [com.apple.awdl:datapathInitiator] AWDLDatapathInitiator clink-ed3b9618b4e0._companion-link._tcp.local <To: 2e:f2:5a:15:76:52> was started

2026-03-19 12:42:01.282537-0400 0x1ae294c  Default     0x0                  495    0    rapportd: (Network) [com.apple.network:path] nw_path_evaluator_start [5C54D967-624D-4269-B080-6C7AE63218C7 IPv6#1e905043%awdl0.49154 generic, attribution: developer]
	path: satisfied (Path is satisfied), interface: awdl0[802.11], dns, uses wifi

2026-03-19 12:42:01.596450-0400 0x1ae253a  Debug       0x0                  382    0    wifip2pd: [com.apple.awdl:driver] Received event realtimeMode
2026-03-19 12:42:01.596589-0400 0x1ae253a  Default     0x0                  382    0    wifip2pd: [com.apple.awdl:interface] Realtime mode updated true

I noticed that on iOS 26 and iPadOS 26 a realtime mode was added specifically to the Wi-Fi Aware API which I assume does what I want: https://developer.apple.com/documentation/wifiaware/waperformancemode/realtime, but I am looking for a solution that works with the existing network API and also on previous OS versions. I have already tried a lot of things, but is there any way to programmatically trigger “realtime” mode?

For additional context, the goal here is to have extremely low latency that also works for gaming. The actual latency introduced in 1 is approximately 30-50ms around once a second… adding a buffer to the stream makes the video completely smooth, but the extra delay on the receiver end is not acceptable for this use case.

Any help or ideas would be appreciated. I can’t easily share a reproduce case right now, and even if I could, getting multiple devices into the exact state along with the router configuration in order to reproduce is going to be pretty difficult anyway.

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Answer 1

DTS Engineer OP

Apple

1w

is there any way to programmatically trigger “realtime” mode?

No.

Well:

Not as an API that’s documented to have that effect. It might be possible to find some API that does it as a side effect, but that would be an implementation detail and thus not something you’d want to rely on.
And there’s the Wi-Fi Aware option, but you’ve ruled that out.

I think you should create a prototype based on Wi-Fi Aware and see if it achieves the latency goals that you need. If it does, you can then factor that into your decision as to how to proceed here.

And apropos that, you wrote:

I am looking for a solution that works … on previous OS versions.

Note that Wi-Fi Aware requires iOS 26 and specific hardware. The main framework doc page has the list.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

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Answer 2

craigc123 OP

1w

Hi Quinn,

Thank you so much for your reply. I appreciate it. Just wanted to ask a followup related to this:

It might be possible to find some API that does it as a side effect, but that would be an implementation detail and thus not something you’d want to rely on.

I understand that this is not something to rely on, but do you have any recommendations of things that might work here?

I already tried creating separate peer-to-peer TCP channels with heartbeat messages, tried using the Multipeer Connectivity API with MCSession to establish connections between the devices (although the actual video packets were still sent via NWConnection), etc.

I find it a little frustrating that the best options as of right now to reduce latency appear to be:

Change your router to use specific channels
Drag your cursor from your Mac to your iPad prior to starting the stream transmission (if transmitting to/from Mac and iPad)

I am aware the Wi-Fi Aware API may help so I probably will look into that separately, however, that still seems to only offer limited support seeing as it is only available on iPhone and iPad at the moment so there is no macOS option, and I intend to add a tvOS and Vision Pro receiver as well.

0

Answer 3

DTS Engineer OP

Apple

1w

do you have any recommendations of things that work here?

No, sorry.

I try to avoid speculating in general, and especially so in cases like this.

tried using the Multipeer Connectivity API

Multipeer Connectivity won’t help. It uses the same peer-to-peer Wi-Fi infrastructure as Network framework.

Oh, and it’s best avoided anyway [1].

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

[1] One day I’ll succeed in my efforts to get that API officially deprecated, and I’ll sing a happy song while I update the advice in TN3151 and Moving from Multipeer Connectivity to Network Framework (-:

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