There are 3 common points of failure:
1. The cable - vendors on Amazon sometimes substitute cheap cables for the ones you ordered. The cables may appear identical but they don't work reliably. Cable can also have damaged internal wiring from being kinked just one time. Or you simply got sent a factory defect
Solution: try another cable from a different vendor. Don't buy the least expensive one
2. Phone - the port in the bottom picks up pocket lint and causes intermittent connection
Solution: have repair shop in the mall clean out the port. They have the proper tools and experience to avoid causing damage. I had this problem and store didn't even charge me. If you attempt it yourself you may cause short circuit- especially if not powered off.
3. DJI Remote Control - the port can get bent from prior attempts to insert micro USB cable upside down.
Solution: unfortunately this is very hard to repair and most people wind up buying a new RC
Hopefully you just got a defective cable or have some debris in your phone's port. It's worth figuring out because OTG is great
