2.1A don't seem to be enough to use both usb ports at the same time.
I have noted that when I connect any combination of: iphone 6 phone, samsung galaxy 5 phone or ipad air, both devices start having problems with charging. what happens is that both start to connect and diconnect, and not charging. Is this because 5V and 2.1A is the max i can get from both USB ports combined, and not each. or why?. This means I can really only use one port at the time when charging my devices?