I think have done this before, but will do it again. My modem is a SpeedStream 4200.I have settled on ubuntu until I have resolved this issue at least.
I ran sudo pppoe conf. It told me my network provider was not found (Access Concentrator....), and suggested that I check my cables.
I have always suspected that there is something wrong to do with the DNS, as I can ping my ip address but not the DNS.
I also think SpeedStream 4200 are a problem in Linex.