I've just moved my modem over to my new CATS machine to find that it
doesn't appear to work reliably...or at least something doesn't.

Until yesterday, I had an external modem connected to my A7000+, running
1.3H (ish - userland not quite up to speed with kernel).  It was quite
happily demand dialling to U-NET for our flat network.

However, when I moved everything over to the new CATS machine, I found
that the modem dials out and connects correctly, but then connections hang
after a few minutes.  tcpdump shows nothing unusual (AFAICT), and pings
continue quite happily.  telnet connections appear to just stop, giving to
response to "Are you there?"s, or anything else.  Same behaviour for ftp
and http as well?

This occurs for connections directly from the CATS machine and indirectly
from the other machines.  When the connections stop, there is no modem
activity or anything reported in tcpdump.

Has anyone seen this before/know what config option I've missed or
whatever?

Thanks,
David.

PS - The CATS machine is running a new kernel that I compiled from the
source tree supplied with it (I think it's 1.3G), because I needed ppp
support in the kernel.