Normally attendance information is directly pulling from finger print device to cloud server. Some various reasons it may be failed to communicate with server.
Here are some ways to check the failure
1) Check whether service is running or not
One way that works in all versions of Windows is to use search. If you are using Windows 10, click the search box near the Start button, and type “services.” Then, click or tap the search result with the same name.
OR
Press the Win + R keys on your keyboard, to open the Run window. Then, type “services.msc” and hit Enter or press OK.
In the service list, find BluelotusAttendance/ BluelotusAttnServices and check the status is 'Running' or not. If there is no status please start the service.
2) Ping the IP Address in Command Prompt
In Windows, hit Windows+R. In the Run window, type “cmd” into the search box, and then hit Enter.
OR search cmd in windows search
At the prompt, type “ping” along IP address you want to ping, and then hit Enter
If you get "Destination host unreachable" then you need to check your internet connection and the cable