I had the machine on this morning, went for a cuppa and when I got back there was a red light on the router to show no connection.
The computer could see the router.
restart but no joy. changed the filters, no joy.
check BT for probs, none in my area.
change cable between router and socket, no change.
connect router directly to the master socket, no joy.
Phoned BT. Got through to an Indian with an english name.
Two and a half hours later. still no internet.
Engineer phone call arranged for tomorrow.
Started emergency tidy up.

Bugger me! Five min after ending the call the damn thing connected all by itself. See how it goes now. Laptop doing 100MB worth of updates.
I'm presuming it was a fault at their end wot they did not own up to.
To be fair to them I got through very quickly, the lady on the phone was very good and this is the first prob I've had since I first started using the web via BT with a 56k modem