"It really is ridiculous and misguiding especially for someone who is curious to move to another home and wants to know what speeds they'll get."

You'll never know what the exact speed will be. Internal wiring might be awful but you won't know until you're in a property.

Maybe the meters you're using should be metres then the speed might increase.

Yes, if internal wiring is the cause for the reduced predicted speeds then that would be understandable. But all the flats under the same postcode in the entire residential block shows identical speed estimates, that can't be right.

If it's internal wiring at least we know this can be sorted out or have a new line installed. But of-course if the problem is external such as very long lengths of copper to the cabinet then that is something beyond the users control.

For example here's another observation I have spotted. I live in a high rise 20 floor building. The checker shows identical speed estimates from 1st floor to the 20th floor.

Now I don't see how that can be right when people living in the first floor are meant to be around 60 metres lower than the top floor for my building which, should constitute to increased cabinet distance. There should be at least slight differences in speed estimations even if all are achieving 80Mbps download speeds.

The problem with FTTC is that you will never be 100% certain what speeds you'll get without actually being in the property, like you said.

FTTP will be the only sure way to get the guaranteed speeds without worrying about copper quality and length as that won't be a thing anymore.

Perhaps in the case of the OP with his cabinet at 1.2km distance speed estimates are going to be less accurate. I guess at the end of the day, cabinet distance is a more important factor in determining what speeds you'll get. If cabinet is under 400 metres users should pretty much get 80Mbps. But when it's longer than that then you have to trust to luck and estimator may be less accurate.

Actual speeds can be affected by internal wiring , but the estimated speeds are set to the Distribution Point, which would probably be the same one for the whole building.

based on you being 1.2km from Cab - the difference in speeds indicates you migth be some distance from your Pole or Footway box as speed on FTTC is normaly determined to DP . are you pole fed or Underground Fed, and is so where is your pole / footway box your property is connected to in relation to your property

Thanks everyone for contributing.

My speeds were simply being 'capped' or to use the official term, my line was 'banded'. The banded profile limited my download speeds to 20mbps maximum, but in reality I was only getting 10-15mbps.

This was against the checker estimating I should get 20-40mbps. Now the banding has been removed, I am getting 25-30mbps. This now seems perfectly reasonable based on the checker estimates and my line distance from the cabinet.

In terms of my line, it enters my property from underground via a grey box near the front.

It took a year of fault investigations and engineer visits for the banding to be discovered/revealed/admitted to by Openreach and the ISP. No fault was every found or identified on my line.

Previously, Openreach would just apologise that I was too far from the cabinet to get higher speeds and push me to purchase FTTP on demand (£17,000)