jakaskerl
thanks for your response,
The oak-d-cm4 is composed of a Raspberry 4, an Intel movidius VPU, a color camera and a stereo camera, all welded on a board. From the point of view of Depthai library, host and device are on the same motherboard so I cannot figure out where the usb connection between host and device would be.
By the way if the warning of slow usb connection is not worrying, I am fine.