cam2019

we will see how long it does work after a reboot

Measure 5V line on USB port to see if its within tolerance. Running low on ideas ... ofc it can be some hardware defects - in that case we both waste time.

Or quirky driver/hardware combo which we didn't make and will not even try to fix.
 

when you did try different boards - did you also try all of the !three! usb-ports on every board?
specially the single one on the other side of the eth0-port? Because in you first dmesg the USB-Ethernet adapter was recognized as eth1 and then renamed.
And this renamed name wouldnt go in every situation automatically up for ifconfig.
 
So check the other usb-ports and when you will see enx00e04c680046 in dmesg get him up with
ifconfig enx00e04c680046 up
and then he would be displayed in
ifconfig
 
when the port is down (not automatically up or no cable/link connected the interface is in down state) then it wouldnt displayed by
ifconfig
 
The part after enx is the MAC-address of your USB3.0 Ethernet-adapter.
 
I got this model running on my devices without special power supply and from my personal view there is no driver problem with armbian and this device.

in his first dmesg it was recognized:
 
388 [ 5.571663] usbcore: registered new interface driver r8152 413 [ 5.906764] r8152 4-1:1.0 eth1: v1.09.9 414 [ 6.188868] EXT4-fs (zram0): mounted filesystem without journal. Opts: discard 415 [ 6.552250] r8152 4-1:1.0 enx00e04c680046: renamed from eth1 but not in the second one.
@cam2019 did you use another USB-Port? Maybe that has to be enabled in armbian-config -> system -> hardware ?