@eddy989 

Hi,

What about the "Internet" LED? (the rightmost one on the front panel of the C80, indicated by a globe with satellite pictogram)

Does it light up in orange or green color when the C80's WAN port is connected or is it completely off?

In case the "Internet" LED is off, then try to get another Ethernet cable to connect the WAN port and test again if the LED come on or not.

If still no success, then connect the WAN port of the C80 to another Ethernet port of another device and check again if the LED comes on or not. (if you don't have another device with Ethernet port, then you can also just loop a cable from one of the C80's LAN ports to the C80's WAN port)

  @woozle well I noticed when connected to any of the LAN ports and in access point operation mode, the internet LED sometimes comes orange but after I power cycle it stays off, but I still get internet, haven't tried the loop yet though. But if I try the loop and the LED doesn't come on or the WAN indicator on the management page "archer c80" tab doesn't indicate then what do you suggest I do then?

  @eddy989 

Like terziyski said, you should test it with at least one more (known-good) cable before any conclusions can be made.

If the Internet LED always stays dark when you are connected via the WAN port, even when paired with another cable or device, then the WAN port may be faulty and you should check if your C80 is still under warranty.

  @woozle my thoughts exactly, tried the loop with two other cables and another TP-Link router( though a lower model), and the cables worked fine with the other router but not with my c80, so I'm now quite sure the WAN port is faulty. Need to go check the warranty and get it fixed if I'm still under warranty. I think I still am though because it's been just about 3/4 months since I got this c80. Thanks for all the support guys 

QUESTION... can frequent power fluctuations and trip off/on cause this current fault to the WAN port? I'm based in a country where that is quite normal......

  @eddy989 

Electronic devices for household use should be designed so that they are able to withstand repeated power off/on cycles, even if it's a type of device that most users will have powered on continuously. 

However, if the mains voltage fluctuated to higher-than-normal levels that could certainly be a problem, but even then I would expect to router's power adapter to be the first thing that breaks.

  @woozle true, thanks a lot for the support was truly helpful. by the way how do i check the warranty on my device or is that specific to the vendor i bought it from?

  @eddy989 

Normally the warranty period is defined by the law of the country you live in and it starts at the date that is printed on the proof of purchase (i.e. receipt).

In most countries the vendor who sold the product is responsible for fulfilling warranty claims.

Some manufacturers also offer an extended warranty (or even "lifetime" warranty) for certain products, but I doubt that is the case here.