Cisco Linksys EA4500 - Unable To Setup Router

I just bought a new router for my home network. It is the Cisco linksys EA4500. It looks great and is rich with features but I just wish I didn't buy it!

My old wireless router started to have its wireless signal very weak, hence this new linksys router. When it is time to setup the router, I just did what was supposed to be done(which is very straight forward, just a matter of choosing pppoe and inputting a username and password) and went ahead to test the internet connection which didn't work! Upon inspection, I discovered that the lights on the internet port on the router(WAN port) didn't turn on at all as if the cable wasn't connected. I quickly checked all connections and to kill any doubt I reconnected the cable to the old router to make sure it is working and it worked. So there is nothing wrong with the cable!

I tried everything one can think of to no avail. The only conclusion one would draw from this whole scenario is that the new router is bad. So, I took it back to the shop I bought it from and before giving me another one, he said he will test it out and I said okay. Surprisingly enough, it just worked !!! Don't ask me why but it just did work beautifully, although at my house if you plug the cat6 cable(that you know for sure has internet) into its internet port, it won't even turn its lights on.