BTW Performance Test - "acceptable range of speeds"

[#1]

My FTTC connection (Value Fibre,so capped at 37mb/s) has been having problems lately. (I won't bore you with the details - I've reported a fault and Plusnet are trying to deal with it.) I've been watching my BT IP profile decline over the last few days. The latest result is lovely:
Download speedachieved during the test was - 15.63 Mbps
For your connection, the acceptable range of speeds is 20 Mbps-15.96 Mbps .
Additional Information:
IP Profile for your line is - 15.96 Mbps
I've not seen a result before where the first figure in the 'acceptable range' is higher than the second figure. Is this a definition of 'unacceptable'?

[#2]

I think this is normal when you have a fault.
When my fttc had a fault last time it had 78-42mb as the acceptable range.
42 is what it was connecting at, with the fault and 78 the usual line speed
If the bar is red and not green and it offers you further tun/tap test, you have a fault.
Just wait for support.