2.4.20-8 was the out-of-box kernel. Since then, there were eight
updates from RH (the last to 2.4.20-31.9), and there _may_ have been
further errata available from download.fedoralegacy.org, although
officially, RH9 is beyond 'end-of-life'.
[compton ~]$ head -1 rfcs/ppp-numbers
[compton ~]$ grep 8057 rfcs/ppp-numbers
8057 IPv6 Control Protovol [Hinden]
You'd have to look at the peer's setup.
What problem? The peer asked if you wanted to speak IPv6. Your
pppd replied "never heard of it". Apparently, you then negotiated
another protocol, probably IPv4, and things are great. Or is your
Red Hat box getting peni^Wprotocol envy? ;-)
For what it's worth, "linux.redhat.ppp" was a mirror of the Red Hat
PPP Mailing List, and it's pretty dead now - I've seen ten posts
since July first.