Who is currently providing your broadband ? , if you are on Openreach it’s quite possible that an issue with your ‘line’ is causing it to underperform , that issue could be in the external in the Openreach network, or internally within your property .
As an example, say you and your neighbours all were a similar distance to the FTTC ‘cabinet’ on the same type of infrastructure, ( served from the same distribution point ) and in general were predicted to get around 60Mb , and most get that , but one ‘line’ had an unreported fault on it that was causing the line to underperform and actually deliver 40Mb ….because there is ‘real’ data showing the line is providing 40Mb ( even though in good condition it would do 60Mb ) the estimates on checker sites etc are based on the real data , not a mathematical model , hence why some near neighbours can have different estimates speeds , if the underperforming line gets its fault fixed , the actual speed improves , and the real data shows this , and that flows through to the estimates sites that show the increase too.
Post your router connection stats , they may show an issue , but obviously if you have a fault ( that you may be unaware of ) it’s your current provider that would need to get it looked at , not BT .
