Hi Jangutter,
Thank you for the posts. We have information that by default, the driver in promiscuous mode does not strip VLAN tags and the capture software
is responsible for enabling the promiscuous mode.You may refer to this site under Linux* for reference:
Network Connectivity — My Sniffer is Not Seeing VLAN, 802.1q, or QoS Tagged Frames
Please do let me know if the information help.
rgds,
wb