Mark paced the server room, the hum of the cooling fans doing little to soothe his nerves. The CEO was expecting a productivity report by noon, but the Kerio Control dashboard was mocking him with a persistent, red-lettered warning:
In this guide, we will explore and provide a step-by-step troubleshooting sequence to restore full web filtering functionality.
Ensure that the Web Filter service is active and has not expired.
The Kerio Control web filter is an essential feature that helps to protect networks from malicious and non-productive websites. When the web filter is not activated, and categorization is disabled, it can lead to security risks and decreased productivity. By following the steps outlined in this article, administrators can fix the issue and ensure that the web filter is working correctly. Regularly updating the Kerio Control software and categorization database can help to prevent such issues in the future. Mark paced the server room, the hum of
When you see this warning in your (usually under Dashboard or Security logs), it means the system cannot reach the third-party classification services—specifically Zvelo —or the license authorization is failing. Common Symptoms: Users can access websites that should be blocked. Internet connectivity may be intermittent or slow.
Go to . Ensure DNS forwarding is configured properly and that the firewall itself can resolve external queries. Step 3: Check Time Synchronization (NTP)
If the licensing is correct and network connectivity is verified, a corrupted local database file may be blocking the service from starting. Clearing this cache forces Kerio to download a fresh categorization architecture. The Kerio Control web filter is an essential
If DNS fails, check your DNS settings in (try 8.8.8.8 as a secondary). If TCP connect fails, your upstream network (or ISP) is blocking these domains, or you have a routing issue.
Navigate to and look at the License tile, or go to Status > License .
Click the button and accept the security warning. If TCP connect fails
Confirm that your subscription is in good standing and your hardware UUID matches the registered asset.
The Web Filter license has expired, or the 21-day Zvelo authorization token has failed to renew.
In the field, input high-availability public resolvers like Cloudflare ( 1.1.1.1 ) or OpenDNS ( 208.67.222.222 ).
: Ensure the "Kerio Control Web Filter categories and applications" rule is enabled under Content Filter > Content Rules .