ftp://ftp.draytek.com/Vigor2760/Firmware/v1.0.2.1/

Annex A firmware is the one you'll probably want

I get the impression that the router is using VLAN tag 101 (which BT use for FTTC) for something internal, which is kinda funny if that is the case and I hope they fix it soon.

there is a new beta 1.2.0 at UK download page which fix few issues (not know which ones as there is not release notes) ... one of them is the wifi led will operate and have add few more features such ... ipv6 (i don't see the PPP) ... bind ip to mac ... bandwidth management for wifi ... option via wan interface to add modem codes (but not any out yet) ... worth to try it