My disconnected from about 10 meters. The remote started beeping even though it was disconnected, it was like it was connected but not receiving any signals or stick inputs. It started RTH straight away and landed safely.
Yep, as said by others, phone have severe limitation, 100 m(Distance), 50 m(Height) (Unobstructed, free of interference). Most only got 80m and yours sounds about right.
Yes, phone has its limitations. I used to control spark with my iphone and get 60m or so before disconnecting. Then i ordered the remote. Night and day difference. You should get the remote. Its transforming a toy into a drone