When the server is down if you start agent it tries to connect but cant but then it does not try to reconnect in like 5 mins or 10 mins so that makes a problem. Maybe you should implement a feature like reconnect if fails in every 5 mins.
2006/09/11 09:33:35 ossec-agent: Connecting to server (10.1.X.X:1514). 2006/09/11 09:33:35 ossec-agent: Starting syscheckd thread. 2006/09/11 09:38:57 ossec-agent: Server unavailable. Setting lock.
