I had a similar problem on OS X Yosemite: I’m able to connect through afp, but I wasn’t able over Yosemite to connect using WD client Apps (I just realized that yesterday), my WD Book Live 1TB was connected to a switch connected to my Airport Extreme. I had changed that arrangment and connected the switch to my Time Capsule that was connected to my Airport Extreme. IiMac 27 " is connected to that same airport extreme.
I had made a new arrangement and connected directly the WD Book Live to Time Capsule ethernet ports and Now I can see the unit.
Will test to see what happens…
