Once you are logged in, register the appliance first. After the registration, follow the steps below.
Navigate to Network > System > Interfaces. Change the X0 configuration first, and then X1, as shown below. You will lose access after you change X1.
Before changing the X1 Interface IP, take a screenshot of the current configuration. The Default Gateway and DNS Server 1 should remain the same and ensure you won’t lose access to the active firewall during the following steps.
After the changes, the Interfaces should look similar to the screenshot below: