Verify sync server status
If your sync server is down, data cannot be synced to and from Cloud. In case of a Cloud sync speed warning, the first thing you should verify is the status of your sync server. In an installation with multiple scan servers, verify which machine is your sync server. You can do this by browsing to the Configuration\Link With Cloud Site menu of the local web console. This menu lists all of your scan servers and clearly indicates which one is the sync server.
Locally on the sync server, open Windows Services and verify the status of the Lansweeper Server service. This service is responsible for all of the scan server's activities, including the sync with Cloud. If the Lansweeper service is not currently running, start it. If the service was previously down and you've since restarted it, be aware that you should wait a while for the Cloud sync to catch up and for the sync speed warning to resolve itself.
Verify internet connectivity and speed
Of course, the speed of your internet connection also has a major impact on the speed with which your data can be synced with Cloud. Make sure your Lansweeper sync server has access to the internet, that you have sufficient bandwidth and that your speed is stable. If you recently resolved an internet connectivity or speed issue, you should wait a while for the Cloud sync to catch up and for the sync speed warning to resolve itself.