Although I have other EX2 Ultras that I could potentially test this on but everything has been carefully mounted on shelves now so I decided to bring this up on the forum.
I can mount a My Book Duo on port 2 without any problems and in order to have two My Book Duos mounted, I simply daisy chain them since the My Book Duo has two USB 3.0 ports on the back.
Do I have a broken EX2 Ultra or is everyone having the same problems.
yes the usb port 2 is broken on this one of my EX2 Ultras.
Yesterday night due to excessive activity on one of my shelf EX2 being connected directly to my wifi router, I decided to swap the ex2 on the shelf with one of my ex2 behind my desk that is connected to a switch. I then proceeded to connect my two USB My Book Duos to each USB port on the back of the EX2 and they both mounted without any problems.
I did do a search on this particular problem and apparently I am the second person to post about this.
Thus the answer to: if a USB My Book Duo doesn’t mount on one of the USB port and does mount on the other, then it is a hardware problem.