I followed this setup here as I bought a kit from them:
I have a BT Home hub 2 and it does not support IPv6 so I had to disable it, I followed this:
And the issues are that some adverts are blocked and some not, Yahoo is the biggest issue so I assume some adds works with IPv6.
I spent 3 days tweaking had all sorts of results, I first had adverts blocked on PC and not on my android device and also the other way around not both. Now only some adverts are blocked on yahoo. I done so much playing around with BT an pihole settings i'm at a lost.
I hope I provided all that I needed, I cant think of anymore. Sorry I cant be anymore specific, I have learning difficulties and this is such a deep learning curve. I never did anything like this before.