The value n is the number of seconds an Application Server (ECP client) should keep trying to reestablish a connection before giving up or declaring the connection failed. The Application Server (ECP client) continues reconnection attempts at intervals scheduled by the ClientReconnectInterval until the full ClientReconnectDuration expires.
10–65535 seconds. The default is 1200 seconds (20 minutes).
On the page System Administration > Configuration > Connectivity > ECP Settings, in the This System as an ECP Application Server column, edit Time to wait for recovery