5.30 may have been impacted by a u-boot issue. I have attempted to use 5.31 image on a Lamobo R1, and the ethernet device would detect, but not send traffic. To test it, I downloaded the 5.25 image and ethernet worked perfectly immediately. To determine if u-boot or something else was the problem, I proceeded to upgrade a single package at a time to determine which was stopping the ethernet from working. I start by upgrading linux-image-next-sunxi and reboot. Upon reboot, the ethernet device stopped working exactly as it did with the 5.31 image.
I'm currently in the process of