Google Nexus 5 :: Auto Backup Via Photos App Keeps Failing

Both my wife and I have Auto Backup turned on in the Photos app. Almost invariably, when we take a look at the pictures in the app, the latest pictures have the little badness icon (triangle with an exclamation mark instead of the cloud with a check mark) on them. There's also a nice message at the top saying Auto Backup has failed. If we hit Retry, almost invariably, the backup happens fine and those icons convert to the goodness icons. This is while we're sitting in our house with a perfectly fine WiFi signal that we can use for any other process without trouble. I remember seeing something when the phones just came out about WiFi issues.