Balance380 HW5 No wan3 port

I have a Balance 380 HW5, FW 6.3.4 build 3613, and I found that I don’t have wan3. There are 4 RJ45 on the front panel, lan1, wan1, wan2, wan3, but in the system, I connect the network cable to lan1, and there is no response. When I connect wan1, it is a lan network. The physical wan2 is the software wan1, and the physical wan3 is the software wan2. I didn’t find whether there is such a setting. I reset the device, but it still happens. I want to know how to solve it. If anyone knows, it would be greatly appreciated. I can’t see the mac address of wan3 in the status bar of the settings and in the interface.



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