Hi Ray,
I assume you want us to capture the network traffic I/O from the OS’s Ethernet port, and not a requesting client? This will require either adding a hub (not a switch) between the OS and the TP-Link/powerline adaptor or enabling port mirroring of the OS Ethernet port if you have a managed switch. You would then need to connect to an open port on the hub, or the mirror port on the switch using another machine with wireshark/tcpdump (with it’s NIC in promiscuous mode) to capture the traffic.