Why is my umbp connecting to my AEBS at only 2.4 ghz?

[Whackintosh]

This is strange, my Imac is connecting at 5Ghz but my late 2008 umbp is connecting at the 2.4 ghz frequency. Wi-fi is notably slower on my MBP than it is on my Imac. Is there anything I can do to change this and force it onyo yhe 5ghz channel?

 

[pellets007]

System Preferences>Network>Advanced and drag the 5Ghz network to the top of the list.