I am developing a USB networking accessory using the CDC ECM or NCM protocol and I would like to know what are the MacOS and iPadOS requirements to connect to such a device.
I have a prototype CDC ECM device developed that uses static IPv4 addressing which I can connect to an Arch Linux host and ping, but I am unable to have the same success from my Mac Studio M1 running Sequoia 15.1.1. The device shows up under 'Other Services' with 'Not connected' status, whether I leave it with the default settings or change it to 'Configure IPv4 -> Manually' and then set the appropriate IP address / Subnet mask / Router.
From a discussion on Github, it seems that the ECM device must support NetworkConnection notification in order to work with MacOS. Can you point me to where this is documented and whether there are other expectations/requirements around USB network adapters?
My end goal is to make an embedded device that communicates to MacOS and iPadOS devices/apps over USB CDC NCM with a simple UDP socket listener.
Thank you in advance for any help you can provide.