Cellular Radio module antenna

Any RF experts out there?

Does the antenna that is included with the Cellular Radio module require a ground plane?
It looks like if it is attached to the circuit board it would have a ground plane. However, I have mine going through the side of a plastic enclosure. I get very unreliable connections. Using a small mag mount antenna makes a big difference. Maybe its just the quality of the antenna and that it can be mounted higher. I’m just scratching for some answers.

If it goes through the side, it sounds like the antenna is horizontal? If so, try it orientated vertically. Polarization counts.