I use an LG Stylo 2 as my device. It's a phone that no longer works as a phone as I have upgraded there. (Bought the Stylo 3) I have tried to use just the WIFI connection and it is virtually useless. The lag is so bad that it takes almost 10 seconds for things to happen on screen. (Ex. I turn the Spark while hovering, 10 seconds later, it finally happens on the screen.) OTG works a million times better for me. No lag or any other issues. I'm on Android and have all the latest firmware and app updates as well. The only problem I have experienced was while flying one day when the KP index was a little high. Lost GPS lock and had to bring it back manually. I've tried using my Stylo 3 for flying. I think being it's my daily driver phone, I'm just using too much processing power. But I will only fly using OTG because it's just a way better connection. I've been out to almost a mile and had no cut outs or anything and truthfully, I don't really need to go that far most of the time. So unless DJI actually disables the OTG, I'll stick with it.