God, the first generations of both USB and Ethernet cameras positively SUCKED. Flaky, buggy, and expensive. Our first foray into Ethernet cameras was from a company called Opteon. They had taken a stock Intel ethernet card and flashed custom firmware onto it to support their custom framing. If the cards and the cameras didn't match exact versions, you could end up bricking one or both of them. They had to be sent back to the vendor to be fixed.

edit: Oh, hey! Opteon still exists! I'm sure their products are much better than those first generations.

https://www.opteontech.com/products/cameras