protocols

I want a router for 1gbps speed. I am planning to purchase TP-Link TL-WR841N (802.11 b/g/n)which has WAN port of 100mbps speed means I can't get speed of more than 100mbps. How much I will get max value practicaly assumming I am using cat 6E cable. WAN port speed how to find? Is it like b/g/n...