That sounds impossible.
If you are using ethernet for BT why not use it also for the thinkbroadband test? If you are using wifi for the BT test then near-identical loss should occur.
Bear in mind that wifi speeds can vary dramatically within seconds, and if something on the computer you are using is doing anything at the same time as your wireless test, or any other device is using the internet at all - wired or wireless, the results of that test are junk.
Edit! I missed that you are on Infinity 1. It is impossible to get a speed test result of 55Mbps on that, as it is the maximum connection speed. From that there is the IP Profile and other overheads to take off. Your maximum speed test result is going to be under 53.3Mbps
Further edit: I just realised you are possibly talking about the 55/10 product, not your connection or speed test result from BT.
First, wireless speed tests are always suspect. Wired are far more reliable. Second, try this test
and click the Further diagnostics
button at the bottom if the initial results page. Then copy and paste the full contents of the two text boxes. We don't need to see the graphics or other stuff.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
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Edited by RobertoS (Wed 15-Mar-17 14:03:00)