My experience with OTG. Does not work with Android properly. I now use my wife's old iPhone 6 as a dedicated device (with the latest iOS and DJI app updates, but has no cell service). Connecting the iPhone to the RC via WiFi I still get unnerving dropouts. Using OTG the DJI app is Rock solid. It is good enough to fly only using the screen video and data; I am becoming more and more trusting in the setup sometimes letting my spark out of eyesight. I do NOT shut off wifi, but I deleted the RC wifi connection. I have the iPhone connect to my Pixel 2 XL for internet so it gets map updates, firmware downloads, etc. VERY important and this is very weird... If I connect the OTG cable first with everything off, the connection does not work. Power on RC, power on Spark, let them connect. Start the DJI app and let it boot to the Device Disconnected screen. If I then plug OTG into RC and then to iPhone, it does NOT work. Plugging OTG cable into iPhone first, and then into RC is the ONLY way everything works. You will get a device unsupported warning, just say OK. Enter the device and you will find everything working better than you have ever seen before. Been using this method for the last 6 weeks, through several DJI updates, and am completely satisfied.