the answer isd in post #4 Universal Repeater mode here http://www.tp-link.com/en/article/?faqid=348

about What i must do? I want to put the antenna at my rooter so my wifi network have more range...i must put it as repeater,right? if you are using WEP security its Universal Repeater mode here...

its not 255.255.255.1 its 255.255.255. 0 in case you use NOD 32 antivirus read here http://www.tp-link.com/en/article/?faqid=358

you posted it doesn't appear in the wifi list of my computer (Windows 7) 7510 its a 5GHZ device, unless the wireless adapter of your laptop has 5GHZ capabilities and by your post its doesnt.

once you change network lan to 192.168.1.254 if no luck, i advice you to add WPA security to your Dlink if possible, with WEP security 730 Ver 2 will give you issues. once you have all devices...

you posted on #3 how can it be possible that, leaving the "wrong" setting, the Internet connection is working randomly then, enjoy your randomly Internet connection