Is there any error message when your try to connect? If you disable Wi-Fi security, can you connect iPhone 6+ successfully?

All other PCs except the desktop installed WN8200ND work properly? Did you try to uninstall the driver and reinstall it? If it doesn't work, try chipmaker's driver(RTL8192CU)....

Upgrade latest firmware for RE210 first. If it is convenient for you, upgrade W8980 as well. http://www.tp-link.com/en/download/RE210_V1.html#Firmware...

Range Extender mode 1 - In Range Extender mode 1, the AP with WDS disabled will relay data to an associated root AP. AP function is enabled meanwhile. The wireless repeater relays signal between its...

To avoid such a problem, change Address Type from Smart IP to Static IP and set each of them a proper IP address which is in the same subnet as the main network.

I can connect internet by directly plug in cable to computer with service provider details. You have to configure static IP, default gateway, DNS on your PC to access internet with direct connection?...