The problem I have had is when I go to do an update of the map, or make some other change, or I need to use a different function on the phone (It does so many things) and I'm out of coverage range (NO SIGNAL TIME) I can not return to the map. With the Garmin we used last night.. no problem since the map is "on board".
And where I am just now, "No signal" used to be very very common... (They fixed it for me in many areas just last week).
A restaurant where, on Good Friday Eve, I had NO SIGNAL.. Last night when I returned with my sweety (The Peach Cobler, A-la-mode, is better than.. Well you can guesws what it's better than). I had half scale on the meter and 4Glte. type improvement. I had a good signal (4g up to the point where I entered the RV) all the way from Town to parked. First time I've ever seen that on tisplay,,, ANd Wi-Fi in the motor home (Anywhere in the RV park).