Since my apple upgrade I can only connect to my WD when I first boot up Mac. It will stay connected as long as I want but if I close the Finder window and try and reconnect it says “Connection failed”. But it still shows “My Book Live” as an option in the navigation sidebar. I’ve tried Apple support and they say WD software not up to date with latest OS. Also had WD look at it but they say alls OK. Never had this problem with Maverick OS or the upgrade to Yosemite OS. Any suggestions or work arounds?
Please check that you have the option for the unit to reconnect at logon
See if the following link helps.