As @Da Flex mentioned. I don't think it's a S/W issue as I have had no issues connecting 2.4 nor 5GHz (Mind you my RPi is ~2M from my router)
As an addition. Try moving your RPi closer to the router. Also, don't use any cases - especially aluminium heatsink cases that cover the whole RPi as this will definitely interfere with the reception of the internal wifi chip.
For the *best* reception, it's better to use an external antenna rather than the internal one - actually it's better not to use the internal wifi at all with LE unless you have a really good reception.
this does solve the issue...
