need to set static ip on your computer lan card
read here http://www.tp-link.com/en/faq-710.html

In home networks IP addresses aren’t usually fixed. This way your router can transform it automatically, if your configurations changed. Static IP doesn’t change. But it's available only at home. So, if you go anywhere with your computer, your IP will change. If you want a different IP at home, you wouldn’t be able to get one. You may hide it only using a VPN. Anyway, static IP address have many advantages. It’s better for using VPN services. You may access to many websites easier apart your geographical location. And static IP is good for creating and hosting computer servers. Changing your IP should be just fine.