Did you read the article here? http://www.tp-link.com/en/faq-911.html

Internet works on PC2 but you cannot the router page? Can you ping router's IP successfully? Did you ever connect it directly to your router and access its web interface?

Wi-Fi is connected but no internet access? What's the IP address, default gateway etc. obtained? If you configure static IP, does it work?

Olivier, VR900 supports NAT loopback but you have to upgrade the latest firmware first. http://www.tp-link.com/en/download/Archer-VR900_V1.html#Firmware

The pin/password on the bottom of the router is a WPA2 password. It is not accepted by your Mac? You may try to log in its web interface by any of other computers. Go to Wireless Settings and...

You may try to disable power-saving to see if it helps. http://forum.tp-link.com/showthread.php?3666-how-to-solve-some-powerline-adapters-can%92t-be-waked-up-by-some-network-adapters