Ok this is a weird one and I hope someone can help with this issue.

We are a multi campus (3) secondary college, each campus has there own
context below the root, two Netware 6.5 server per campus. A few months
ago I start upgrading our server hardware, did one campus worked fine no
problems at all then I upgraded a server into a different campus/context
exactly the same server hardware, NW OS, SP6 and patches.

The issue:

All of a sudden half (NOT ALL) staff and students only in that context
couldn't login to the tree, the workstations would just sit there trying
to authenticate then 5 to 10 minutes later get this message - "Connection
to the server terminated" our netware client is the same version across
the college (4.91 SP3), searched around for days but couldn't work out why
this was happening then I reset one of the users passwords and the user
could then login to the tree!! Next day the same thing happened not all
the users I reset could login again, so once I reset the password again
they could.

I thought it may have been the server build so I removed DS and rebuilt
that new server, once I rebuilt that same server the login issue started

There is nothing wrong with any other part of the tree, all replicas are
fine even on the new server, have done DS Traces but nothing looks out of
place. I have removed and reinstalled licensing but this didn't help.

The new server is configure exactly the same as the other 6 NW 6.5 servers.

If anyone has seen this issue before or could offer some advise it would
be greatly appreciated.