Whenever I connect my iPad (non-cellular / wifi-only version, so no sim card and no mobile data connection) to my Mac over USB, I get a dialogue box stating that a new network connection iPad-USB has been found and asking whether I want to configure it. I realize that it in principle is for using the iOS device as mobile hotspot, but with this iPad model it's not even possible to use it as a hotspot. Why does macOS bring up the dialogue nevertheless?
I would like to prevent this dialogue box from appearing each time I connect the iPad to the Mac. I had the same issue with the iPhone, where I resolved it by activating the mobile hotspot in the system preferences on the iPhone (mobile data section), configuring the network connection iPhone-USB on the Mac, and then deactiving this network connection. With the iPad, this strategy does not work: I can not activate mobile hotspot on this iPad (there's no mobile data section in the system preferences), and I don't even see the iPad-USB interface as an option when trying to add a new network connection in the Mac's network preferences. Yet the dialogue box that appears on connecting is stating just that.
In case it matters, the system details are: iPad Pro 2015 (12.9'') with iOS 11.2.5, MacBook Pro 2017 with macOS 10.13.5.
You are probably referring to this message:
From today's point of view, your Mac's behavior is a bug. Maybe the iPad advertises its Bluetooth to be a network adapter? Like WiFi or cable network adapters, Bluetooth chips have a MAC address. Here, MAC doesn't refer to Apple's computer brand, but to a universally unique identifier. See for example the https://macaddresschanger.com/bluetooth-mac-lookup
iOS does support the Bluetooth personal area network to route data packages to other devices, potentially connecting to their internet: https://developer.apple.com/documentation/multipeerconnectivity
Theoretically, the iPad could connect to the Internet via a Bluetooth-based personal area network. Currently however, the iPad's Personal Hotspot feature until iOS 12 only supports sharing cellular data. I am not aware of any plans that might change that.
Maybe your Mac is ready for the day a future iPadOS or iOS version extends the Hotspot feature to Bluetooth?
You can try to log into macOS using an admin account. Maybe the Network Preferences sidebar allows you to delete the iPad. If yes, then you shouldn't see the message anymore when connecting it via USB.