WiFi 2.4GHZ vs 5GHZ

5GHz has a shorter range compared with 2.4GHz;
The 2.4GHz frequency is way more crowded than 5GHz, devices on 2.4GHz suffer much more interference than the ones on 5GHz;
Fewer devices are capable of using the 5GHz channel than the 2.4GHz channel.

Also read http://www.howtogeek.com/222249/whats-the-difference-between-2.4-ghz-and-5-ghz-wi-fi-and-which-should-you-use/?PageSpeed=noscript for more info.