Is it possible for you to place the router and PC next to each other? If the signal strenght is full, what's the speed? Try channel width 80Mhz or 40Mhz.

Maybe it is based on security consideration.

System light should be flashing. Your device is faulty. Try to get a replacement under warranty.

What is static device? DHCP clients list C7's webpage is not what you need?

The WLAN dongle is also TP-LINK? Hope the latest firmware could solve the problem. Good luck... If not, report it here, http://www.tp-link.com/en/Support/contact/.

You didn't get it. Maybe your username or password has been updated or changed by your ISP. You should confirm with your ISP. If they are correct, maybe it is router issue. So disconnect it and...