Before you log into the setup page, you need to set a static IP first for your MAC pro. Go to the System preference-->Network-->Ethernet-->Advanced-->TCP/IP-->Configure IP v4-->Manually-->IPv4 192.168.1.10,Subnet:255.255.255.0,-->Apply. And then try the Setup page again.

thank you, I did that and my computer says that Im connected, but if I write the 192.168.1.254 into firefox it doesn't open the setup page!

How about reset the tl-wa5210 and then try on another computer? What is more, you can also try to ping the IP address from the computer or check whether the IP address is correct or not.

thi, I have restart it, seems to be the same. dont have another computer....the computer says that Im connected but the setup page doesnt open

grrr

Go to applications folder---utilities---network utilities---ping:
Enter the network address to ping: 192.168.1.254
Click on ping.
Check the results. You can see packets transmitted, received and loss. If it fails, double check your configuration, If it is ok, try different browser.

thank you mavis and mynetwork, I managed to contact to the device, now I want to make my device as a repaeater, as I have many neighbours around me I have their network name and password but when I want to set wireless security the WEP does not work, Im not so good in that part, I put all different options but it never pass thru: for example I have these network and passwords: 1. ZOJA pass: zoja 12, Borutol_wifi pass princeska and TP-LINK pass zorvelikonja, I dont know what kind of security this is)=? hexadecimal or what should I do, thank you in advance, or you suggest something else=?

Here is a instruction on how set up the 5210 as an repeater, hope this can help: http://www.tplink.com/en/article/?faqid=348
5210 only allows WEP security. Make sure that your main wireless router did have WEP password because the 5210 should have the exactly same password as main wireless router. Wep Hexadecimal, it can allow numbers and letter a-f.