I use USB phy:Microchip LAN7800. On TX1.
I use JectPack 3.1,and get lan7800’s driver from kernel.
A problem: I unplug the net line for LAn7800 Then power on the decice, the net is down;only if I ifconfig down and up the device.
It sounds like ordinary network configuration…not specific to a Jetson. There are some GUI programs to set up networking, plus there are files you can edit in “/etc/network/” or “/etc/network/interfaces.d/”. The GUI app “nm-connection-editor” might be a useful starting point.