The day before yesterday a huge thunderstorm hit my area. I went out to pick up my dinner and when I got back I found my router not working. It says the WAN cable is unplugged. At first I thought the cable was somehow faulty so I spent quite some time replacing the cable because it was wired to the gateway router down in the basement. After I replaced it, it still says the same error. Apparently the WAN port was physically damaged. I was almost making an order for a new router and suddenly it came to me that this router has 4 LAN ports which can a substitute for WAN port. Luckily the ASUS Merlin firmware let me enable Dual WAN mode and specify one of the LAN port as the primary WAN interface. This saved my day and about $150. Now I know I gotta shut the windows when there are lightnings, especially with my router being close to the window with its antennas sticking out.