opkg install http://dl.eko.one.pl/openwrt-18.06/packages/mips_24kc/base/3ginfo-text_20171227_all.ipk http://dl.eko.one.pl/openwrt-18.06/packages/mips_24kc/base/3ginfo_20171227_all.ipk
uci set 3ginfo.@3ginfo[0].language=en
uci set 3ginfo.@3ginfo[0].device=/dev/ttyUSB1  # or /dev/ttyUSB0
uci commit
/etc/init.d/3ginfo enable
/etc/init.d/3ginfo start

Point browser to http://192.168.1.1:81. For more info see eko.one.pl - Projekt "3ginfo" (in Polish, use google translator).