This is a partial-temporary solution. Basically, if the frequencies are on different channel numbers then it is possible to "set" the particular wifi band (worked on OSX Mavericks). steps:
1. Find the channel numbers of 5 GHz and 2.4 Ghz. Are they different? if yes proceed to step 2.
2. Set 5 GHz channel number using
airport command.
Detailed instructions:
- Open Wireless Diagnostics.app (it is located in /System/Library/CoreServices/Applications).
- In the application menu select Window->Utilities (or press cmd+2).Utilities window should appear.
- Select WiFi Scan from Utilities window and press Scan Now button. This will show you all available networks, info about them and your active connection.
- Now, verify that BSSIDs of 2.4 and 5 Ghz with the same network name are on different channel numbers. If so, then most likely you can change the band by setting the channel number of the desired frequency band. Alternatively for steps 1-4, just type in the terminal
sudo /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport /usr/sbin/airport -s
- Open the Terminal.app and type:
sudo /System/Library/PrivateFrameworks/Apple80211.framework/Resources/airport --channel=num
where num is the channel number to set. This command will only work under administrator account (so make sure that you are log as an Administrator i.e. su YourAdministratorAccount)
- You can check your active connection by re-scanning with Wireless Diagnostics, Alt+Clicking on the WiFi icon on the OSX menu bar, or using the terminal :-).
That's all!
P.S. If you can not set the channel try to turn off the wifi device before using the airport command.