GPS signal - Not good at times (Mavic pro zoom)

[Smartypants2]

Why at times, on clear days do I get better GPS signal then other times? I have had other times when I took off sufficient GPS and while flying I get a notification of poor GPS ( I quickly returned)
I guess I still learning how I am actually communicating with my drone

Am I controlling by GPS ?
Is the camera to my phone based on cell signal?

Thanks in advance
Marty

 

[Starz]

Confusing post. More specific please.