I came across this fact yesterday. Some, but not all, Macs may be experiencing slow Wi-Fi connections. The cause could well be a new feature of OS X Yosemite and iOS 8 called Apple Wireless Direct Link (AWDL). This technology is used for AirDrop,
AirPlay, and direct-play gaming connections. It is also known for causing Wi-Fi problems.
A quick solution can be applied through your terminal (Finder >> Go >> Utilities >> Terminal). Enter this command in your terminal window
sudo ifconfig awdl0 down
You will be prompted to enter your OS X administrator password. This command should clear up the wireless problems, but it DOES disable AirDrop on your Mac.
To re-enable AirDrop, simply go to your terminal again and enter
sudo ifconfig awdl0 up
What this Unix command ifconfig is doing is turning off/on respectively the network interface named awdl0.
Note that changes applied from the command line like described here will not persist after a system reboot.
Some older Macs may not be using AWDL so this command will result in an error message, something like “interface awdl0 does not exist”. I tried this on my Mac Mini (Mid 2011) and found that it was not supported. If you try it and if fails with this kind of error there is no harm done.
See my other Mac OS X articles