As I know, the bug has been fixed with firmware version 140912. Can you try that firmware to see what happens? TL-MR3420_V2_140912 5.Fix the bug that the backup link won't revert to the main link...

What do you mean by Manual credentials? Anyway, it is good to know that it is working now with your modem...

;)I don't know...You can use the beta firmware temporarily.

There is a beta firmware to solve youview IPTV issue on C8. Ask for it from TP-LINK support team and have a try. http://ticket.tp-link.com/index.php?/Tickets/Submit

File name can be created by outselves. What name do you want to change? Provide a screenshot. To disable Media server won't affect local USB sharing... http://www.tp-link.com/en/faq-756.html

Powerline is TL-WPA4230P instead of TL-WPA4230PKIT? Powerline devices have to work in a pair at least. One should be connected to the router and another one or more can be used as the Wi-Fi extender....