Hi. I have a problem between my H520 and my E90. Every time I walk just 100 meters from the st16, I lose communication between them. The secretary is responsible for reminding me again and again that communication is lost. In addition to all the above, there is a quite important lag between the movement of the gimbal and the received image. I bought the device from a friend of mine, so I rule out any problem caused by a crush. Rather, I think the problem is related to software, or perhaps, some kind of calibration that I have not done because of ignorance? Thanks a lot for your suggestions.