@ToddMG,

It is only necessary to have one powerline adapter that is connected to your router however this becomes more complicated if you are trying to use Powerline adapters across circuits, as most signals will be interfered with at the breaker box.

I would highly recommend, if you are looking at upgrading your network, to look at other networking solutions such as our OneMesh solutions for other ways of extending your network. In my personal opinion, if you're house is fitting for the situation, a mesh network will give you a much better experience for streaming high-quality media. 

To find more information about the different powerline configurations, you can browse the FAQs for any of our Powerline Products. The FAQs for the TL-PA7017P, as an example can be found here: https://www.tp-link.com/us/support/download/tl-pa7017p-kit/#FAQs