If your problem is not the same, you'd better start a new thread. So only your laptop has the problem, right? Normally, we use DHCP to obtain IP address. You may try static IP on the laptop to see if...

TD-W8970 itself has no power saving feature. Can you do it on your VoIP phones? am I able to force the ports to 100mbps/full duplex instead of Gigabit? Cannot. We usually do it on computers.

The Max Power Consumption of Archer D9 is 36W with Power Adapter ,and without Power Adapter it is 33W. Does it refer to the max power consumption without power adapter or with it? But you said, "I...

Why do you want to do that? Read the article here. http://www.tp-link.com/en/faq-560.html

Address revervation issue has been solved by the beta firmware, but you have to login its web interface to do that, What's the IP address obtained on your PC connected to C9? Is it correct?

When connection drops, how about status of all lights on powerline adapters? If they are normal, check local area connection. Is it connected? What's the IP address, default gateway, DNS server...