Works great in in ARMBIAN 5.34.171121 nightly Ubuntu 16.04.3 LTS 4.13.14-sunxi64
Fresh install of Armbian_5.75_Orangepizeroplus2-h5_Ubuntu_bionic_next_4.19.20 on new sd card. Simply logged in and changed password as required.
Disabled g_serial in /etc/modules
Then do modprobe g_ether and then dmesg, I get the following
udc-core: couldn't find an available UDC - added [g_ether] to list of pending drivers
Have never build a kernel...