Unless you are flying out to the verges of wifi limits (drone / controller), or have too much interference between drone and controller, then it could be some wifi or cable problem with controller - device connection.
Do you use wifi or cable connection controller to device ?
If using a cable, have you changed cable recently for some reason ?
I have always used cable connection, not sure why, but it probably is to do with me first getting a Mavic Pro, so used to cable connection.
It's always been super reliable for me, so if you usually use wifi, maybe give the cable a shot.
Make sure it's an OTG cable, I ordered spiralled ones from Thors Drone World for mine, keeps cable tidy when using with either ipad mini 4 in controller handle clasps, or in a Lifthor mount.