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This is a good question but I don't think any of the other four replies have understood it. Judging by the original article, this problem appears when AirPlay d

This is a good question but I don't think any of the other four replies have understood it. Judging by the original article, this problem appears when AirPlay devices are on the same network and the same subnet as you. All that should be required to scan for devices on your network is sending a broadcast packet, as you have indicated. What others are claiming effectively amounts to saying that the Macbook needs to disconnect from your network, scan for access points, and then reconnect to the network. Which would certainly cause latency issues, that much is true, but that's surely not the kind of scanning that is actually being done here? Why would a scan for access points be necessary?

saltcured 4y ago
I am not a Mac user, but as I understand the topic, it is using the radio for location and proximal device detection. It is not a LAN feature that would work via broadcast in the current WiFi LAN nor would it work if using only a wired LAN with WiFi disabled. It puts the radio into a different mode to listen for nearby devices, whether to talk to them or to use them as landmarks for location sensing. This requires scanning radio channels, not just continuing to listen to the channel where you expect to receive further packets from an associated access point.
- bscphil 4y ago
  That certainly seems like a plausible thing that could be happening, but the specific claim of the article is that this is an issue with Airplay, which to my understanding involves devices that are connected to your router / access point, not free standing devices with their own access points that have to be scanned for. There might very well be latency issues involved with the WiFi radio scan modes on Macs, for all I know, but I don't think they could be related to this specific issue with AirPlay?
  - saltcured 4y ago
    The problem seems to be that they bundle all these features into AirPlay with the intention of making it easy to use. It uses device discovery that is not bound to the current LAN. See https://support.apple.com/guide/deployment/use-airplay-dep9151c4ace/web https://support.apple.com/guide/deployment/use-airplay-dep91... "When looking for other devices, an Apple device broadcasts a very small Bluetooth advertisement indicating that it’s looking for peer-to-peer services. When any peer-to-peer-capable device hears this BTLE packet, it creates or joins a peer-to-peer network directly between the devices. The devices concurrently switch between this temporary network and any infrastructure networks they were on before in order to deliver both the AirPlay video stream and provide existing internet service. The temporary network typically operates on Wi-Fi channel 149+1, but depending on the hardware involved, may also include channel 6, or channel 149,80. The devices follow the same frequency use rules on the temporary network as they do with any other Wi-Fi connection to avoid disrupting any existing infrastructure networks that might already be using those channels."

saltcured 4y ago

I am not a Mac user, but as I understand the topic, it is using the radio for location and proximal device detection. It is not a LAN feature that would work via broadcast in the current WiFi LAN nor would it work if using only a wired LAN with WiFi disabled. It puts the radio into a different mode to listen for nearby devices, whether to talk to them or to use them as landmarks for location sensing. This requires scanning radio channels, not just continuing to listen to the channel where you expect to receive further packets from an associated access point.

bscphil 4y ago
That certainly seems like a plausible thing that could be happening, but the specific claim of the article is that this is an issue with Airplay, which to my understanding involves devices that are connected to your router / access point, not free standing devices with their own access points that have to be scanned for. There might very well be latency issues involved with the WiFi radio scan modes on Macs, for all I know, but I don't think they could be related to this specific issue with AirPlay?
- saltcured 4y ago
  The problem seems to be that they bundle all these features into AirPlay with the intention of making it easy to use. It uses device discovery that is not bound to the current LAN. See https://support.apple.com/guide/deployment/use-airplay-dep9151c4ace/web https://support.apple.com/guide/deployment/use-airplay-dep91... "When looking for other devices, an Apple device broadcasts a very small Bluetooth advertisement indicating that it’s looking for peer-to-peer services. When any peer-to-peer-capable device hears this BTLE packet, it creates or joins a peer-to-peer network directly between the devices. The devices concurrently switch between this temporary network and any infrastructure networks they were on before in order to deliver both the AirPlay video stream and provide existing internet service. The temporary network typically operates on Wi-Fi channel 149+1, but depending on the hardware involved, may also include channel 6, or channel 149,80. The devices follow the same frequency use rules on the temporary network as they do with any other Wi-Fi connection to avoid disrupting any existing infrastructure networks that might already be using those channels."