21-09-2023 16:58 - edited 21-09-2023 16:59
Without more information, we can't really make any suggestions.
So what service are you on (brilliant/fab/super) and what speed were you advised you would get when you joined?
Also what speeds are you getting, and how are you testing it, and are you doing so over Wi-Fi or wired?
Maybe take a look at this help page.