• Connect to a physical device using a cable.
• Before debugging run adb tcpip 5555 && adb connect <device ip>
• Remove the cable.
• Now run it in debug mode.
• Verify it can write a document.
• Now put it into standby mode.
• Wait 20-30'ish minutes (in which time Android will shut down Wifi to save power).
• Wake it up and add a document again.

You can see the details in Logcat, at the error-level.

The interesting details to look for, is the difference in time between the local timestamp and the server timestamp.