I am wondering if you have configured the wireless router correctly..You may login to the router's web-based management page and check if you get a WAN IP on the status screen. If the WAN details are all 0.0.0.0, you have to reset the router and reconfigure it. BTW, does AKTA use adsl or cable connection?

It is installed properly because so far it worked. My ISP uses cable connection. Here is a print of web-based management: http://i1266.photobucket.com/albums/jj523/johnb9512/Untitled.png

You think that is necessary an update of firmware? I found some on the producers page put the latest reffers to v4.20 and I have v4.23

From the picture, it seems the router was connected to ISP properly.
You'd better re-explain your problem. Even though you get WAN details on TPLINK, you can not browse internet? The wireless network doesn't work on your laptops? Or sth else?
Besides, your router's firmware seems to be a bit old. It's better to upgrade it. You may download the latest firmware (V4) from their official website.
Then upgrade the firmware by referring to http://www.tp-link.com/en/article/?faqid=296

I've made the upgrade but still isn't working, and yes, this is the problem, I can't browse internet.

Troubleshoot as follows:
1. on the router's page, go to system tools-> diagnostic, ping 8.8.8.8, a proper reply means internet is activated on the router.
2. then on PC, open windows command prompt, ping 8.8.8.8, if you get a proper reply, then ping www.google.com, if it says "...can not find the host...", this could be DNS problem.
Possible solution:
On router's page, go to DHCP, change the Primary DNS to 8.8.8.8
Does the 8.8.8.8 as primary DNS work?

Dude, you're a genius. That was the problem. Thanks a lot!