I'm in the process of upgrading my BT Broadband to Fibre Optic and ahead of the actual switchover I received a BT Hub 5. I live in a part of the house where Wireless is not great and there use Powerline plugs to connect to the internet. With my 2009 Mac Mini (RAM 8GB) and El Capitan I managed to connect both wirelessly and via the TP-Link AV500 Powerline plug. But when I try to connect to the internet on my Bootcamp Windows 7 partition, I cannot get the computer to talk with the Powerline plug and whenever I fiddle around, come up with the message, "Local Area Connection doesn't have a valid IP configuration." When I upgraded from BT Hub 3 to Hub 4, I never had any problems so don't know what's going on and Networking is definitely my weakest area of understanding. I don't know anything to be honest. Can anyone advise me please?

Does your Mac Mini use a DHCP address, or a static one? Also, you probably want to make sure the TCP/IP v4 configuration for your Windows partition is using DHCP, and then you likely should disable IPv6 on it as well.

I've had problems with getting my Mac OS working with the internet too, sporadically. Someone on another forum has suggested that my router, a BTHub5 runs a dual system 5MHz and 2.4MHz and my TP-Link powerline is only geared up for 2.4MHz so I'm trying to figure out how to shut down the 5MHz part of the hub and see if that improves my Mac internet first. I know nothing about networking, a major hole in my computer knowledge, so I don't understand anything of what you say. I think my Mac did use a DHCP address but if doesn't work and comes up with its own IP address, so am manually using, the router address which seems to work . . . when it works. Obviously with the powerline in the way, my computer and router are not communicating very well.

The wifi can run dual 5 and 2.4.... this has nothing to do with the powerline adapter, unless the powerline adapter is wireless and is used as a wifi extender.

What is the make/model of the powerline adapter?

Question 1: When you are in bootcamp, are you connectiong to the Powerline adapter with cable, or wifi. I want to establish if this is a wifi extender of sorts or a more traditional powerline ethernet adapter.

Question 2: If you move closer to the router and plug in there, can windows connect? This takes powerline out of the equation.

Use thid Open a command prompt window by click on start->accessories-> right clicking on it and running it as an administrator. The black command prompt window will open. Now type: ipconfig /release <- then hit enter.
Now type: ipconfig /renew <- and hit enter again. That should force a reset of the adapter. If you want to see what your setting now look like type: ipconfig /all There is a space between ipconfig and the /.