GUtech wrote One more small issue. In the middle where particularly?

Check this http://www.tp-link.com/en/article/?faqid=205

of course you can set up password for guest network. There are password settings right under the guest network menu. You can also disallow the guest to access your LAN. In addition, you can even set...

On the device there is a wireless indicator LED light, is it on and flashing? If not, check the back panel, there is a wifi button, press that button for 1~2 seconds. Then the Led should be on and...

1. Does your WAN interface has a public IP address? 2. Maybe 3389 isnot enough, set up DMZ for your computer

It is a router. The wan port is supposed to connect to Internet. Why took out the WAN?