PopTop, VPN works on only some systems

Ok, I installed pptpd, kernel-mppe, and ppp >2.4.2 on my main system.

I have three systems behind a linux MASQ firewall. No ports are being
blocked, just MASQ going on to share the IP.

One of the three systems can vpn in to the main system 90% of the
time. The other two cannot at all.

When I compare the debug logs, I see that the successful one has an
entry:
GRE: Discarding duplicate packet

just as it is becomes successful. The failures always seem to have:
Dec 18 13:37:07 rh3 pppd[9818]: sent [LCP ConfReq id=0x1 <asyncmap
0x0> <auth chap MS-v2> <magic 0x814a1579> <pcomp> <accomp>]
Dec 18 13:37:31 rh3 last message repeated 8 times
Dec 18 13:37:34 rh3 pppd[9818]: LCP: timeout sending Config-Requests
Dec 18 13:37:34 rh3 pppd[9818]: Connection terminated.
Dec 18 13:37:34 rh3 pppd[9818]: Exit.

Instead.

Anyone have any ideas about this?

Brian Andrus
batman(at)thundermail.com