Nissan made a big song and dance about the new infotainment system on its 2019 Navara, and rightly so, because the vehicle had been off the pace in this regard compared with its major competitors. The changes included the inclusion of Apple CarPlay and Android Auto, but also included full smart-phone mirroring.
None of which is much use to you, Dom, because if the system won’t connect to your phone without dropping out, it’s a moot point, yes? I’d be straight back to the dealer to have it sorted out. The computer that controls the infotainment might need a re-boot or maybe there’s a more fundamental problem. Either way, Nissan’s factory warranty should cover this.
But before you do that, try one thing: Pair the car with a different phone just to rule out the possibility that it’s your phone that the upgraded system doesn’t like.