The BT speed test shows everything is fine except the speed achieved during the test. There are lots of reasons why a one-off speed test might go wrong; perhaps your security software decided to download an update whilst you were running the test, or you have a virus that is using all your bandwidth, or a peer-to-peer program running in the background, or another device on your home network.
The other possibility is that you had a good line when the connection was established which had become very noisy by the time you ran the test. Perhaps you turned the Xmas lights on, for example.
Now you have restarted your router you need to start again from scratch, re-run the BT speed test then try some other speed tests to see if the results are consistent.
