Test your broadband speed from anywhere in the UK . Cloudflare has servers in London and Manchester, so your test runs locally and shows what your line actually delivers, not some best-case number.
The biggest cause of slow broadband in UK homes is still FTTC (fibre to the cabinet) . Fibre runs to the green street cabinet, then old copper handles the last stretch. Speed degrades sharply with distance from the cabinet. If your line is rated for 80 Mbps but you only get 45, you're probably more than 400m away. The fix is FTTP if Openreach has it on your street; check openreach.com/fibre-checker .
100 Mbps is plenty for most households. If you stream 4K on multiple screens and game at the same time, 500 Mbps to 1 Gbps on full fibre is the sweet spot. Below 30 Mbps, multi-device streaming will struggle.
"Up to" speeds are theoretical maximums. What you actually get depends on your distance from the cabinet, in-house wiring, and WiFi quality. Run a wired test first. If that matches the contract estimate, the issue is your WiFi or device, not the line itself.