Newbie bridge question

Hi,

I'm configuring Astaro for the first time as a bridge but I'm quite unfamiliair how to configure this. We have the following situation:

Remote LAN (192.168.2.x) & VLAN 192.168.3.x --> Routing switch ---> 10.40.1.2 ---> Fiberconnection ---> 10.40.1.1 -> Routing switch ---> internal LAN (192.168.1.x) & VLAN 192.168.3.x

Now I want to place an Astaro on the connection between 10.40.1.2 and 10.40.1.1. but since this line transports packets from regular LANs and also a tagged VLAN 192.168.3.x, I can't use astaro in routing mode (as far a I know you can't have tagged and untagged VLAN traffic on the same physical interface). Hence, my idea was to use bridge mode and add a third interface connected to the 192.168.1.x LAN for administring the Astaro. Will this work? Will the VLAN traffic pass through? What packet filter do I need to define so that the 3rd interface is only used for management traffic for the Astaro web interface?

Pardon my questions, but I've never used bridges before.

Franc.