iCloud Photo Library Update Failing

I have a large library of photos that I'm adding to iCloud --17K+ from my MacBook Pro (running Yosemite). The upload is failing, though, and I'm getting pretty frustrated. The upload appears to be working for a few minutes and then randomly, and for no apparent reason, iCloud Photo Library disables itself (unchecked) and the updating is paused. I have the ability click the Resume button but it doesn't resume the upload-- it still indicates that "iCloud Photo Library updating is paused". Restarting the Photos app is the only way to continue the upload, but eventually, it fails. See the screenshot attached -- I've clicked "Resume" but apparently the upload is still on paused.

Any advice or guidance would be very greatly appreciated!