I have a portable hdd in port 1, a usb hub in port 2 with a desktop hdd and WiFi adapter and wireless keyboard adapter, you will not get 2 hdd working in a single port unless you install B Rads firmware.
I use a wireless bridge in the ethernet port instead of a usb wireless adapter. I don’t have two usb HDs hooked up so I’m not sure it will work for your purposes but it does free up an additional USB port.