In the Member Interfaces list box, select LAN and DMZ:
Enter a brief description in the Description text field (for example, LAN-DMZ bridge).
Click on the Save button.
We now have bridged the two interfaces, but unless the firewall rules allow traffic to flow between them, traffic will be blocked. Therefore, we will add firewall rules to allow traffic to flow between LAN and DMZ:
Navigate to Firewall | Rules.
Click on the LAN tab.
Find the IPv4 default allow LAN to any rule and click on the Copy icon for this rule.
Change Interface to DMZ.
Change Source to DMZ net.
Change the description in the Description text field (for example, Allow DMZ to any rule).
Click on the Save button.
Click on the LAN tab again.
Find the IPv6 default allow LAN to any rule and repeat the process to generate an IPv6 rule.
When you are done making changes, click on the Save button.