DJI O3 range

So as I understood, that O3 transmits video to DJI goggles 2 to several kms. But as I flew behind my house (20m from where I sat), the signal got lost. I tried 2 more times and it was the same. Signal lost and I crashed. Question: did I forget to do something/turn something on? How do I fly several kilometres away then, if I lose picture flying away 20 metres?