On the affected Windows computer where the Worry-Free Business Security Services agent is installed, make sure to have a good Internet connection and then do the following:

1. Check the Windows/Router Firewall settings for any restrictions and do either of the following:
   • Allow the Worry-Free Business Security Services communication ports. Refer to this article: Open a port in Windows Firewall.
   • Turn off the Windows Firewall. Refer to the Microsoft article: Turn Microsoft Defender Firewall on or off.
   • Allow the Worry-Free Business Security Services Official Components URL list.
2. Verify if the computer uses any proxy settings. Refer to the Microsoft article: Using Proxy Servers together with Internet Explorer.
    

   If you are using proxy, allow the Worry-Free Business Security Services Official Components URL list on Bypass Proxy.

    
3. Open a Command prompt, ping the WFBS-SVC servers, and press Enter. Below are the WFBS-SVC Servers:
   • US and other regions: wfbs-svc-nabu-aal.trendmicro.com
   • Europe/Middle East/Africa (EMEA) Region: wfbs-svc-emea-aal.trendmicro.com
4. On the command prompt, run the "tracert" command to the Worry-Free Business Security Services servers, and press Enter.
    

   The expected results from Step 3 and Step 4 will be "Request timed out". These steps are to ensure that the machine can resolve the domain name of the Worry-Free Business Security Services servers.

    
5. Use magic link to reactivate the agent. Refer to the article, Using the Install Link by Group feature of Worry-Free Business Security Services.
6. Click the Windows orb, type "services.msc" on the Search field, and press Enter.
7. Check the following Trend Micro services and make sure they are started.
   • TrendMicro Common Client Solution Framework
   • TrendMicro Security Agent
   • TrendMicro Security Agent Firewall (if enabled)
   • TrendMicro Security Agent Listener
   • TrendMicro Security Agent RealTime Scan
   • TrendMicro Unauthorized Change Prevention Service
8. Restart the Trend Micro Client/Server Security Agent service. 
9. Unload and reload the Worry-Free Business Security Services agent on the system tray. Refer to this article: Unloading the Client/Server Security Agent.
10. Restart the machine.

If the issue still occurs, contact Trend Micro Technical Support and provide the Case Diagnostic Tool (CDT) log generated on the client computer.

For the instructions on how to get the CDT logs, refer to this solution: How to use the CDT to collect all the information needed by Trend Micro Technical Support.