Thank you for your post. First in regards to the speed of the connection check the link below for recommendation on settings. Note that in the 2.4GHz spectrum there is the most amount of interference; in this case the speed would decrease. The maximum speed possible with this adapter would be 300Gbps.:
What are the recommended settings for 802.11n connectivity?
Now in regards to the 5GHz that cannot be detected by the adapter, most of the Intel® Centrino® Advanced-N 6200 adapters are capable of 5GHz, except for the 622BGHMW model. You might want to check with the laptop manufacturer if the laptop was designed for 5GHz support, for this support they would have needed to go through additional validation and installed a specific 5Ghz antenna.
I just had this problem myself. I just discovered I had to change the default settings in the device properties.
Click start ---> right click Computer ----> properties ---> Device Manager ---> Expand Network Adapters ---> Right click Intel(R) Centrino(R) Advanced-N 6230 ---> Advanced Tab ---> Wireless Mode ---> Select 6. 802.11a/b/g.
I don't know what 802.11A has to do with Wireless N, but that worked for me.