Go to Properties of network card on your PC and check Speed&Duplex. What's the Value there? Provide the screenshot.

What's the model number of wireless adapter and operating system of your PC? Maybe the following guide will help. http://www.tp-link.com/en/faq-306.html

I just saw that the adaptator close to the modem has no light on, the one connected to the computer has the middle light missing All lights are off on one adapter? Did you try different power...

I'm afraid that W8970 doesn't support such kind of application. It cannot work as a computer.

I've just finished setting up my TD-W8980 router but I've noticed that even if my settings are correct (successfully login) the host entry in no-ip.com doesn't get updated. WAN IP is not updated on...

I think so if it is still under warranty.