>were did you get pppd-2.3.1-6? I run pppd-2.3.0 off a stock 2.1.71
2.3.1-6 is the latest Debian ppp. You must download the new version 2.3.2.
Then you _need_ to compile only the pppd stuff (in the pppd directory) and
overwrite /usr/sbin/pppd executable with the new one (after strip it).
I just do it some days ago and works fine.
Andrea[s] Arcangeli