latest update for this one is here
http://www.linksysbycisco.com/US/en/...W11S4/download
but as far as i can see this will only work with cable not dsl
i would go get a new one
hmm seems there is more than one type of this one
the pdf from
http://downloads.linksysbycisco.com/...S4-v4_ug,0.pdf
seems to not have dsl
but
http://downloads.linksysbycisco.com/...S4-v4_ug,0.pdf
seems to have it doing both so there maybe a firmware that will do it
but still i think a new one would be a better idea