In the Interfaces page of SonicWall GUI, when trying to bridge any two interfaces in layer 2 bridge mode sometimes there is an error message stating "Error: Index of the interface.: DHCP Server enabled on secondary bridged interface - not supported".
Step 1: Log in to the SonicWall Security Appliance management GUI. Step 2: Navigate to Network | DHCP Server page.
Step 3:Disable the "Enable" check box of the DHCP scope (Dynamic or Static) for the appropriate interface to which the layer 2 bridging has to be done. (Here X0 interface is considered) Step 4: Click on "Accept".
Step 5: Navigate to Network | Interfaces page and click on the configure option of the interface that needs to be bridged in layer 2 mode. Step 6: In the new window's General tab, set Mode/IP Assignment: Layer 2 Bridged Mode, Bridged to: X1 (Here X0 is bridged to X1, so X1 is the bridged to interface).
Step 7: Click OK.
After layer 2 bridging is configured, same IP address is present on two different interfaces that were bridged as shown below in the screenshot.