The PC admin was actually quite helpful (a case of beer to their lair
worked wonders) so when he came in and looked at it for a while, he
said I should try a static IP. (The clients machines are on DHCP from
a Windows server in the 10.21.0.xxx range ; the server has a public
address). Static IP's actually helped - but not for long. But at least
he has given me a reserved range of IP addresses, which I fully intend
to use as Plan B if I run out of time. That will mean setting up a
server on one of these addresses and faking a DNS etc.
I've seen issues like this before when hopping subnets like you are
doing. Ideally the server and clients would be in the same subnet on
the same switch, but it isn't always possible.
Assuming you are on 10.3 all the way around login as a local admin and
do a 'sudo killall DirectoryService' and see if the home mount springs
to life. If so then give our SlowDown startup item a try. I wrote it
specifically to solve an issue with flakey home mounts when crossing
subnets.
