Respond to Connection closed abnormally log messages
Logs might contain the message “connection closed abnormally” if the connection closing does not occur in the expected order of a normal TCP connection.
Connection closed by client/by server or connection reset by client/by server messages in logs inform you about an event that the Firewall has detected in the network. Connection closing is an expected event at the end of each standard TCP connection. The logging settings in the Access rules determine whether connection closing is logged. Frequent abnormal connection closing or resets might indicate problems in the network, such as an overloaded server.
Steps
If connection problems affect services, perform standard network troubleshooting steps along the whole communication path.