Older Kerio Control versions hardcoded old IP ranges for the categorization servers. If those blocks were sold or changed, your firewall tries to reach dead IPs. This manifests as a "stuck hot" error where the service cycles between activating and failing.
If the error persists with "hot" status, you likely have a version between 9.2.0 and 9.2.5. Those versions had a known bug where the filter daemon would enter a STATE_HOT_RETRY loop indefinitely. Update to or higher (or 9.3.x) to resolve the hardcoded IP issue. Older Kerio Control versions hardcoded old IP ranges
If your error log specifically mentions "Invalid Authorization," it likely means the has expired (tokens typically last 21 days). Older Kerio Control versions hardcoded old IP ranges
If tests fail:
Go to → Services .