QuickBooks Web Connector may deliver an error message about the sync state when it cannot make a reliable connection.
Common cause: slow internet speed
The first step in troubleshooting is to check your internet connection. Although your connection may be active, it might be overwhelmed with too much traffic or otherwise underperforming.
Solution
If your business uses ethernet connections, you may need to contact your IT support team for assistance with assessing speed. If your computer uses wifi access, first check the status of your connection using the available tools in the Windows Toolbar. Google offers a free Internet Speed Test using your browser that can help identify if your connection is too slow to support the amount of data that you are transferring. https://fiber.google.com/speedtest/
If you find that your internet connection is not performing as expected, you can begin troubleshooting the issue locally.