Hello @dq11,
I just tested with a USB flash drive and get the same error message now. I think you can ignore that error message, because OpenWrt works well even with that message.
Please follow the below connection diagram and you will be able to access Luci Web UI on 192.168.2.1:
Also, the network connection will be successfully routed through the X86 to your connected clients.
Please let me know your results.
Thank you.