I doubt that this is cell signal issue - I am guessing that is just a bug with the car since people don't have this issue with their phones and their phones are using the same wireless network.Driving on 401 between Mississauga and Markham road almost daily and notice the cell signal has gone really bad recently
I often saw 3G and never saw Lte Until reboot MCU
Ending up just turn on the hotspot on the phone and share to the car. Much faster and stable now