OpenWrt USB OTG Serial Setup

config.txt

################################################################################
# Bootloader configuration - config.txt
################################################################################

################################################################################
# For overclocking and various other settings, see:
# https://www.raspberrypi.org/documentation/configuration/config-txt/README.md
################################################################################

# OpenWrt config
include distroconfig.txt

[all]
# Place your custom settings here.
dtoverlay=dwc2

inittab

::sysinit:/etc/init.d/rcS S boot
::shutdown:/etc/init.d/rcS K shutdown
::askconsole:/usr/libexec/login.sh
tty1::askfirst:/usr/libexec/login.sh
ttyGS0::askfirst:/usr/libexec/login.sh

rc.local

# Put your custom commands here that should be executed once
# the system init finished. By default this file does nothing.

modprobe g_serial

exit 0

system

config system
        option hostname 'OpenWrt'
        option timezone 'UTC'
        option ttylogin '1'
        option log_size '64'
        option urandom_seed '0'

config timeserver 'ntp'
        option enabled '1'
        option enable_server '0'
        list server '0.openwrt.pool.ntp.org'
        list server '1.openwrt.pool.ntp.org'
        list server '2.openwrt.pool.ntp.org'
        list server '3.openwrt.pool.ntp.org'