[Samba] Can't see more than 8 files? MTU-ish issue?

[Howard Jones]

A colleague is working with a Samba installation where Windows clients
are accessing the server over a VPN. They are seeing an issue where a
share is visible, but if a directory contains more than 8 files, they
get an error.

The VPN is set to allow everything in both directions. Windows->Window
sharing does work OK across the link, as do other large file transfers
(NFS, FTP). The Samba connections work OK locally, and if the firewalls
are replaced with a router (the two 'sites' were original local for
testing), then the problem goes away. However, the firewall policy
doesn't limit anything (and wouldn't it break Windows too?)

Does this ring any bells with anyone? The firewalls are Juniper
Netscreens at both ends, for what it's worth. I've had a google around,
and I can't see anything related to packet size or MTUs, which is what
it smells like to me... (presumably the 9th filename ends up in a second
packet, or a certain sized response).

Thanks in advance for any pointers,

Howie