BT's network connection regulary drops if you move a good deal away from the router. One of my friends who lives on the same road as me and uses Virgin, gets much wider and faster coverage (even from the garden). Like me, he has router also on the top floor (three floors up) and the wall thickness and the building structure is identical. I am guessing this has probably to do with BT's wireless hub which maybe isn't as good as te router Virgin provided to my friend. Is BT's newest hub better than the one that preceded it? Will it provide greater coverage? I might need to ask BT to send me the new one. Or should I look to buy my own router (a very good quality one)?
You may well have some form of local interference or even congested wireless channels (There are only 13 to go round)
I suggest that you download a small program called inSSIDer that will show graphically all wireless channels and their usage locally to you.
You may find moving the wireless channel to a less congested one may help.
It didn't cross my earlier but I think what I will do is use a long ethernet cable and a long modem-to-phone cable and bring the router and modem to either to the middle floor or even the ground floor.