Packet Tracing allows you to check packet processing flows and identify reasons for packet loss, as shown in the following figure.

Set analysis conditions and click Analyze, the details of packets will appear, as shown in the following figure.

If discarded packets exist, a red icon with the number of discarded packets appears, as shown in the following figure.

To view how a packet is processed by each firewall module, click View Packet Processing Flow. For a discarded packet, you can view where and why it is discarded, as shown in the following figure.