Thanks for the input everyone. To cover the points raised:
Everything is hardwired. If it's got an ethernet port on it, it's plugged in in our house
This is my Netflix app in my Panasonic AX802b TV. As others have stated, the quality increased as the stream starts (like YouTube does when it's on Auto) and there's no way to force it.
Thanks for the points about the single vs multi stream tests - So far all of the single stream tests I've done have been the same as the multi ones but I'll keep an eye on it over the next few days.