it�s easy to lose a lot of speed by something minor happening elsewhere eg having a smart tv connected that�s downloading
Just to clear up any misunderstanding. When I say "actual speed" I don't mean the speed I get on my end devices. I mean the sync speed that I can see in router statistics, along with "attainable speed" which I imagine is the max speed my line could achieve.
So in my case, attainable speed on TT line is around 1730. Sync speed is either 512 or 768 (suspiciously well rounded). TT support copypaste their standard message about speed depending on a number of factors, and insist 768 is what I should be getting, and can't explain what I should do to get the full 1700.
While on BT, the same line was capable of speeds between 2400 and 2600.