Thank you for explaining the set up in detail, my guess is the reason why you're not able to view the wired devices on your network is because the wired connections are going through a network switch. Basically the rocket hub will be able to see the switch connected, but it won't be able to see any devices on it. Because the switch is unmanaged, it doesn't broadcast the IP. This is likely due to a software limitation in the ZTE software.
I'll tag @Datalink@Gdkitty@gp-se for their insight. I'm sure they would be able to shed more light on why this is happening 🙂.