VIO arrived yes! Won't connect to iPhone 6+ Vio app

Hi there, looking for some advice with VIO for scooter. I've done everything by the book, but the darn thing just keeps disconnecting before I can get anywhere with the device - I have an iPhone 6+, the latest Vio app installed, have tried deleting app twice, doing a 20 second reset on the VIO... all to no avail.

Anyone got any connecting advice please before I return this to Amazon??