Presuming you have an HH5 until you post the stats from troubleshooting/helpdesk (lines 1-12) we'll never know.
Otherwise post a speedtest Further Dignostics result from BTWholesale.
Trty a factory reset of the HH5 with pinhole reset for 20 secs.
Post back router stats after.
|1. Product name:||BT Home Hub|
|2. Serial number:||+076272+NQ44112469|
|3. Firmware version:||Software version 22.214.171.124.126.96.36.199.6 (Type A) Last updated Unknown|
|4. Board version:||BT Hub 5A|
|5. VDSL uptime:||0 days, 00:46:58|
|6. Data rate:||19854 / 76562|
|7. Maximum data rate:||35312 / 84121|
|8. Noise margin:||10.0 / 8.5|
|9. Line attenuation:||0.0 / 15.4|
|10. Signal attenuation:||0.0 / 15.5|
|11. Data sent/received:||37.8 MB / 291.6 MB|
|12. Broadband username:||email@example.com|
|13. BT Wi-fi:||Yes|
Done and results posted above. Already max data rate is continually falling.
what about your connection speed? is it stable?
If you compare your first post of your data stats you can now see the Max Attainalbe has shot up.
Next questiions are how are you connecting and if wireless have you tried a wired connection?
All ISP's are required to supply is a wired connection at or above the minimum speed they sold it at. There is no ISP that can or will guarantee a wireless speed as there are too many variables not under their control.