Cannot. IP address should be in the same subnet. Change your seagate central's IP or C2's IP.

Bad luck. Your device is being faulty. Go back to the verdor and get a replacement under warranty.

I have no such a unit. Read UG or contact their technical support to confirm. http://www.tp-link.com/resources/document/TL-SG105E_V1_UG.pdf http://www.tp-link.com/en/Support/contact/

Try repeater or range extender instead of powerline devices.

Did you check status page of TD-8817? http://www.tp-link.com/en/article/?faqid=547 What's the hardware version and firmware version?

Technicolor 582n is not a dual band router, isn't it? Since the old one and D7 work similar to each other in signal strength, it means that probably it is a limitation of your network environment. To...