Just bought one AC750 Wireless Dual Band Router, Model No. Archer C20 from flipkart and as it's recieved today just an hour ago I tried to configure the same but it's keep on showing WAN Cable in unplugged however it's certainly not. I've already tried reseting router to factor settings, reinserting the RJ45 in WAN slot multiple times, but as it seems it failed to identify the cable.

Please help me as this is just a new product got delivered to my home.