I have two ADSL lines with an ISP which supports multilink and two Alcatel
USB Speedtouch modems on one linux machine.

Using the Alcatel Speedtouch driver in the linux kernel (2.4.23),
ppp-2.4.2b3 with the pppoatm plugin and the latest speedtouch firmware I
can connect to both lines separately AND together fine. However, as soon
as I add the 'multilink' option to PPP option file, it stops working when
trying to connect the first line and ppp dies, regardless of which line I
try first.

Jan 2 22:32:51 router pppd[247]: Plugin usr/lib/pppd/2.4.2b3/pppoatm.so
loaded.
Jan 2 22:32:51 router pppd[247]: PPPoATM plugin_init
Jan 2 22:32:51 router pppd[247]: PPPoATM setdevname_pppoatm - SUCCESS 0.0.38
Jan 2 22:32:51 router pppd[248]: pppd 2.4.2b3 started by root, uid 0
Jan 2 22:32:51 router pppd[248]: PPPoATM set to VC multiplexing
Jan 2 22:32:51 router pppd[248]: using channel 1
Jan 2 22:32:51 router pppd[248]: Starting negotiation on 0.0.38
Jan 2 22:32:51 router modprobe: modprobe: Can't locate module
Jan 2 22:32:51 router pppd[248]: ioctl(SIOCSIFMTU): No such device
Jan 2 22:32:51 router pppd[248]: Exit.

There's nothing else in any of the logs to give any clues apart from
above, even with the debug and kdebug 1 options.

I have all the kernel PPP options (including multilink) compiled as
modules, and without the multilink option ppp loads them all just fine, I
don't know which module it is complaining about.

Can anyone suggest anything I could try to get to the bottom of this? Am I
using the latest ppp or where can I get the latest development version
perhaps?