There is 4 usb ports. Here is where I have soldered the cable to the PCB:
I looked into Flash/ram upgrade but I thought I am no longer so skilled to try the soldering. Hopefully I found the 4th usb I have installed usb drive inside the the unit (pendrive fitted above RJ connectors under the aluminium cover).
Now I can do what I dreamed to do - place all the firmware to the flash (ok, to the internal usb), so I can freely control hdd on/off from a front side button, and I still have 3 usb ports
Speaking about external usb ports - I would love to put there USB sound card and plug USB keyboard to control playing of internet radio stations. Have anyone managed this? I found somewhere one of such posts but the links did not work - seems too old.