Hello,
I would suggest you to download TCPdump from Services -> Package manager, if it is not already installed.
Then, navigate to System -> Administration -> Troubleshoot and in the troubleshoot section enable TCP dump. This will allow you to select network interface you want to monitor, set a few filters, if necessary, and begin packet capturing. The capture file can be downloaded from the same section later. For more details check this page.
You can also start TCPdump via SSH and monitor the live packet capture or save captured packets to file.
Best regards,