Trying to get my head around BI hardware setup

I'm not sure. It seems to somewhat support it (hardware does support it, software is questionable). There are talks of some newer firmware being maybe released at some point that would support VLAN tagging better.
Currently it looks like it supports VLAN for a single LAN port, but it's set up more towards IPTV setups that usually run on a specific VLAN ID, specified by the ISP. Not really sure how it all plays with firewall rules etc.