I have had S. Fast BB for 2 weeks....getting 77+ upload / 17+ DLoad speed...so that's good. We had a BT "Dual band wifi extender plug placed downstairs ( main hub is upstairs) when we had our last provider......kids complaining that when they are downstairs signal not good / dropouts....do I need to "Tell" this extender that main PC now has SFBB?....I mean...should I have done something when I 1st set it up? thanks
They are intended to be entirely automatic, and don't care how you get your broadband. All the adaptors should need is an ethernet connection to your main router.
You may need to look for other issues, such as electrical interference on the mains.
I may have completely misunderstood what kind of extender you have.
If it's a wireless repeater (no wired link back to the router), then you will need to re-program it to repeat the new broadband, not the old one. You'll have to find the instructions for how to do that.
I was thinking of powerline adaptors, where one unit connects to the main router by an ethernet cable, and the other links to it through the mains wiring.