1 | initial version |
Could it be that the PLC packets coming from the mirror port are VLAN-tagged? In that case, you might need to change some registry settings to make the NIC pass on the packets. You might also need to change some registry settings to make Laptop-C show the vlan tags (as the NIC driver will normally strip them before NPCAP sees them).
Have a look at: https://wiki.wireshark.org/CaptureSetup/VLAN
Also, I assume you are using promiscuous mode on all 3 laptops and no capture filter. Is that correct?