Maybe you guys can give a feedback to TP-LINK support at support@tp-link.com wish they can produce an effective instruction~

Try to reset your WA701ND and Thomson st585 Router. Change another security type to have a try~ or if it's possible, change another router to have a test.

Grg wrote So, accidentally i find a solution of my problem! The problem was the MAC Address Filtering. I had it on both on the wr340 router and on the wa730 extender. Then i disabled it in my router...

never meet the same situation, but I think it's hard to make it~

try to use two TL-WA5210G to set point to point bridge mode refer to the following link: http://www.tp-link.com/en/article/?faqid=176

no idea about this~