Welcome to the forum
You have given very little information to work on. For instance, what sketch is running on the Uno, how are the commands sent to the Uno from the PC, what format are the commands in, how does the Uno communicate with the software on the drone, how is the project powered, does it share a common GND with the PC, does the drone hardware share a common GND with the Uno, do all devices use the same signal voltage level ?
Please post the sketch, using code tags when you do, and a schematic of your project, a photo of a hand drawn circuit is good enough