LAN ports of PA4010 and WPA4220 are only 100Mbps... After upgrade the line, the speed is limited by powerline devices in the network actually... Check the rate via TP-LINK utility and connection...

Find the right guide for you here and have a try. http://www.tp-link.com/en/search/?q=voice+mail&t=FAQ&s=

Refer to the post here. http://forum.tp-link.com/showthread.php?78963-Can-someone-post-their-settings-config-file-for-Archer-c7-v2-as-an-AP&p=156734&viewfull=1#post156734

Did you try to install the driver for Window 8 or 8.1？ With limited connectivity, IP address is 168.254...? Can you try static IP?

I contacted TP-LINK support team on this issue and they said "they are pushing chip manufacturers to provide drivers for Windows 10 as soon as possible"...

It would be better to add a range extender or powerline devices in your network to extend Wi-Fi range.