We can login its web interface to go to Quick Setup to configure it.
http://www.tp-link.com/en/faq-87.html

M Diamond wrote

We can login its web interface to go to Quick Setup to configure it.
http://www.tp-link.com/en/faq-87.html

I'm already in the web interface, and when i try to access Quick Setup or any other setup wizard I get "Error Code: 10" message.
So what is Error 10? or where can I find any list of error codes?

Try different web browsers or different computers if possible.
Check connection between your PC and LAN port of WR841N.
You can also go to Network---WAN to select the connnection type. If it works. go to Wireless to configure SSID and password.

Already did this things, but always the same problem - Error Code: 10

That's Weird...
Can you provide a screenshot of the error?
The router is a brand new one?

Router not new but work perfect till last days.

Go to System Tools---Factory Defaults to Restore.
If it cannot be displayed, hard reset it by pressing reset button for 10 seconds. Later, try the web interface again. If it is the same, try to get a replacement under warranty.