You might be getting hit by BT's Fair Usage Policy (FUP). Try downloading outside of peak hours (peak: 4pm - 11pm). There's more info here
BT Broadband - Wikipedia, the free encyclopedia

You could try changing ports...no guarantees that it'll help though! In LW go tools > options > advanced > firewall config. Change LW's listening port to 64049 (or try other ports in the range of 49152 - 65535) > Apply > ok. If you change listening port, you'll also have to change port forwarded within a router.

There's some info about the HomeHub here...might help you with the password?
BT Home Hub explored