This is odd. First, my configuration: Orbi 963 - Router.
RAX-200 - in AP mode connected to Orbi via Ethernet.
USB HD Drive connected to RAX-200 via USB (Readyshare) mapped as a folder on my laptop.
Laptop connects to Orbi via WiFi or Ethernet.
So, when the laptop is connected to my network via WiFi, I can get to the mapped Readyshare drive. When connected via Ethernet, the laptop doesn’t see it. Everything is on the same network 192.168.1.xx
