Help!! What is TAP 3

I'm trying to find out my current IP Profile, but when running the http://speedtest.btwholesale.com/ page and selecting 'Further diagnostics', instead of getting the 'sending to server' response I'm getting 'Best effort service for TAP 3' where another speed test is done.

Could someone explain why this happens?? Is there another way of finding out my current IP profile (I'm with Plusnet, but their 'current line speed' is rarely in line with the BT one)

Try with a different browser maybe

are you saying that you do not actually get passed onto the Further Diagnostic web page (and hence passed to something else) or you go get there but the advanced test using your telephone number fails with the TAP3 message you stated

Well that is exactly what I was saying! Anyway, I rebooted the PC then the tester worked! Odd