My first Inspire (bought Jan 2015) has always had issues with flying past 500-600 meters. Once beyond that range the RC signal drops and presents me with a low signal warning.

My second newer Inspire can fly past that range but has another issue.

This newer Inspire has an issue with the video signal dropping during flight. This one had an issue with the camera from the beginning and was replaced by DJI after it just stopped working. Once I got it back with a new camera, it still has issues with dropping its signal during flights. When its on the ground its fine. Once I start flying that's when the issue starts. Ive checked and cleaned the connectors and made sure the Micro SD card is inserted correctly.

At this point Im not sure what to do. Each has their own issues.

Sorry, but it sounds like it needs to be send in one by one for testing and solving problems.