This Counter64 counts URL access authorization requests re-sent by the firewall to the specific URL Filtering Server represented by this row because a response wasn't received within the configured interval, counted from the last reboot of the managed device. An admin can use it to spot which individual server is running slow enough to trigger retries before it escalates to outright timeouts. A row whose retry count is rising steadily while its response time also climbs would point to that server becoming progressively overloaded.