I doubt your WR740N has a problem... http://www.tp-link.in/support/rma/

So strange...Maybe it is a DNS issue... Can you ping google.com and ping 8.8.8.8? Can you disable Wi-Fi security and try if it works? On Status page of C9, there is WAN IP address, right?

On your wireless devices, can you login web interface of C9 with http://192.168.0.1? If you reset the router, did you reconfigure Wi-Fi name and password? Can you forget the Wi-Fi network on iOS...

Unfortunately...yes...no QOS function.

You can make it work in bridge with AP mode but it will disconnect constantly? Refer to the guide below and check your configuration step by step. If the problem continues, you may contact the...

You are right...It is running the latest firmware now. http://forum.tp-link.com/showthread.php?80292-TL-PA4010-drops-multicast-packets&p=158193&viewfull=1#post158193