The Plus Net portal tells me that I should be using PPPoA and VC Based multiplexing. Now I believe I have been using these settings for the last 2 years or so, but today my router (Netgear DG834G) simply wouldn't connect. In the end I let the router configure itself (not holding my breath) and it chose PPPoE and LLC Based multiplexing. These settings seem to be working, but I am a little bemused a) why would the settings suddenly need changing and b) I am using exactly the opposite to what Plus Net advise :?
If that's the case I had something similar with my Linksys WAG54Gx2 - In the end I had to update my firmware to the latest version, and ensure that the multiplexing settings were ok as the router no longer autodetected them.