Sky broadband embed user login credential in their routers. If you want to use a third-party router, you have to use Wireshark to sniff it out[(http://www.skyuser.co.uk/forum/sky-router/55168-extract-username-password-sr102.html) (https://www.youtube.com/watch?v=BdcsmYX7eEQ)]. Here is a summary of what you have to do:
The modulation settings should be[(http://forums.digitalspy.co.uk/showthread.php?t=2033907)]:
The whole point of extracting user credential is to make it work with OpenWRT. You might want this[(http://wiki.openwrt.org/doc/uci/network#pppoa_adsl_internet_connection)]. Please note that there are apparently two ADSL annexes[(http://wiki.openwrt.org/toh/buffalo/wbmr-hp-g300h#configure_adsl)].
Finally you definitely want to delete all the existing ATM bridges. Otherwise your ADSL won't connect.