I am unable to establish a data path from a Raspberry Pi via the Microchip PoE USB-C adapter.
Failure to establish some data connection is a disappointment but not a surprise. Data via the USB-C on the Pi was an unknown entering into this RoadTest. This post will provide the setup and configuration details that were used in the testing. The plan for the review process is to make another post seeking E14 Community assistance in finding a solution. As was mentioned in the introduction, the RoadTest Review is about the Microchip PoE USB-C adapter and not the Pi. It is important I keep that focus.
A data connection between the Pi4B and a laptop was established using On-The-Go (OTG) support (upper drawing). When enabled OGT established a USB0 network interface on the Pi. The interface was assigned an IP address and using SSH a network connection between the laptop and the Pi worked.
The Pi4B was then installed in a network as represented in the lower drawing. The USB0 interface was displayed on the Pi terminal using the ` ip a ` command but there was no IP address enabled on the interface. Moving the Pi back to the original network configuration, the interface with the assigned IP address was present.
The answer I suspect, is in the details from the pamphlet provided with the Microchip PoE USB-C adapter. "If the USB host doesn't recognize the PD-USB-DP60 as a USB device please go to the LAN7800 product page to download and install the appropriate device driver.