pfSense as a transparent bridge

[tomasz1919]

God day to all.
I have installed pfsense on my Odroid H2 with 2xNIC and need your help with setting up pfSense as a bridge.
At the moment my house network looks like this
Static IP provider--------ASUS router------switch----devices
Asus router does port forwarding and also managed local network.
I would like to have pfSense in this configuration:

StaticIP provider-----pfSense bridge ----ASUS router----switch---devices
with all the settings on the router I have at the moment. In case I am away from home for 3 weeks and Odroid will have some issues , my wife can simple unplugged the FW and get back to previous installation.

So far I have followed the post
https://support.adamnet.works/t/running-on-a-transparent-pfsense-bridge/79

and did as follow:

1. disabled outbound NAT
2. net.link.bridge.pfil_bridge set the value to 1
3. net.link.bridge.pfil_member to a value of 0
4. create and enable bridge interface
5. OPT1 - I have set IP address from pool of LAN of my router without setting upstream gateway. Here I have problem what IP and gateway shall I use since pfSense in on the WAN port of router and I don't have any upstream router as shown in this tutorial.
6. Set WAN and LAN interfaces and set the IPv4 and IPv6 configuration type to None
7. Configure Firewall: WAN interface created a rule that passes all traffic over the interface.
8. Configure Firewall: Created a rule that passes any traffic to the OPT1 net.

Thank you for your time and answering.