If you are on the FTTC 80/20 package, loads and loads of people on the BTCare forum are seeing the same issue. I would guess over a hundred people have reported it.
Basically all of a sudden their speed drops from e.g. 72 megs to sometimes under a meg! A Homehub disconnect and reconnect seems to sort it ... there seems to be no need to power cycle the hub or touch the white modem. Simply log in to the hub manager and simply do an internet disconnect follwed by a reconnect.
You get a new IP as well. If it doesn't fix the problem, try it a couple of times, it does seem to be based on the IP you get.
I found that there was also an event in the hub event log which shows that there was remote access (by BT) to the modem, which coincided with the disconnect and subsequent massive drop in speed.
Speed tests show the IP Profile has not changed.
Som esay it's faulty home hubs, and this is what the call centre will say - ie they may send you a replacement. Other times they wil ltell you that a hub reconnect is "normal Sir" - even if you have to do it every dayl it seems (a total load of bull, I think .. but who am to say ).
The fact that a config is being requested by the B T remote access would perhaps seem to point to events on the backbone causing it - maybe their routers are having bits of routing changed, and then every now and then this causes your IP to behave erractically in terms of routing and ping. Only a thought, no proof at all.
But, you may wish to trundle over to
http://community.bt.com/t5/BT-Infinity/bd-p/BTInfinity
and see what others are saying ... and join in ...
Cheers,
Rob