I am actually able to control my Canon T4i DSLR using a flashed portable WiFi router and an app from the Play Store called "DSLR Controller" by Chainfire.
Out of the box the app is designed to give you full control of a Canon DSLR using a USB cable, but on their website ( https://dslrcontroller.com/ ) they go into detail on how to hack a specific type of portable battery powered wireless router to allow your phone to talk to your camera over wifi. Honestly It is not a super elegant solution but it does work well overall.