If you're one of the many iOS 8 and OS X Yosemite users who have been plagued with Wi-Fi issues, here is some good news: Mario Ciabarra, the co-founder and CEO of Colorado Springs-based Quantum Metric, claims to have found the root cause of the problems, and has also come up with workarounds.
Ciabarra says that he has narrowed down the issue to the use of Apple’s Wireless Direct Link (AWDL) that is used for AirDrop, AirPlay, and Gaming connections. "I’ll go out on a limb and say the WiFi issues are because of Apple’s choice of using Bonjour over AWDL and that, given the constraints of the Wi-Fi hardware, this will be difficult to get right." The solution, he suggests, is to disable AWDL.
iOS 8 users will need to have a jailbroken device, as the fix involves a tool called WiFried which Ciabarra claims allows users to enable/disable D2DWiFi/AWDL, and can be conveniently turned off under the AirDrop settings in Control Center.
Ciabarra discovered that the issue with D2D/AWDL is also the root cause of the severe Wi-Fi performance degradation affecting users on Yosemite. To fix the issue, disable AWDL and AirDrop using the following command:
sudo ifconfig awdl0 down
Conversely, you can restore AirDrop and AWDL anytime using the following command:
sudo ifconfig awdl0 up
We can't guarantee that Ciabarra's workarounds will work for everyone, but if you are been impacted with the bug, it's at least worth taking a look at. Apple recently released a second beta of Yosemite (10.10.2) after the first beta yielded a formal OS update released to the public last week, failed to fix the Wi-Fi problems. However, it isn't yet clear whether the 10.10.2 update fixes the issue.