Mac Mini connecting to Airport Extreme at only 802.11a, how to push to 802.11b/g/n?

My Mac Mini is capable of 802.11a/b/g. I have an Airport Extreme that is capable of 802.11a/b/g/n. The Mini connects at only 802.11a. It is close and has a very strong signal. How do I push the Mini to reconnect at 802.11g?

Update: I’m using Airport Utility version 5.5.x.

You can disable “a” mode in your Airport Extreme !

Air Port Utility -> Your AE -> Manual Setup -> Wireless -> Radio Mode

To check what wireless mode your Mac mini is using, click at the wireless icon (top right of your screen) while holding alt :

Finally go to System Profiler -> Network -> Airport -> Supported PHY Modes to ensure Mac mini supported modes