Same thing here on a Nexus 6P. Had to revert to 4.1.15 on APK Mirror. Besides to not getting all the data (
battery, GPS, etc) the transmission was solid and I flew a couple hundred meters without a glitch.
I then tried to give Wifi another shot but it's useless. My biggest problem flying with Wifi instead of OTG is that the phone switches to a nearby wifi that DOES have internet. (Maybe an Android Oreo thing). It just does that which actually makes some sense. Why wouldn't it give priority with a connection WITH internet?? If you're in the middle of nowhere, that wouldn't be a problem.
4.1.15 is solid. I'll just stick to it. I assume the problem on 4.1.18 was not intentional from DJI. My son has an iPhone and on iOS, 4.1.18, OTG is still working just fine.
I'm confident 4.1.19 will fix the OTG on Android.