Navigation quits after a while when connected via usb

[GrayHtransit]

Hi, I've got a 2019 Tourneo. Nav works great when I plug in my phone via the USB connections. The trouble is that after a while the nav stops working. If I unplug and replug the usb it works for a couple of minutes only. Any suggestions to rectify please? I'm not that good at phone technology so it could be the van or my Samsung phone.