I have a problem that I have found a workaround for but I'd like to fix

INTERMITTENTLY a workstation won't be able to login to a Novell server.
It will give me mapping errors. I have found the error was caused by
the workstation mistakenly believing the server didn't exist and
putting the server name in it's bad server cache. I can turn off the
cache and fix the problem.

However the real cause of the problem is a TCP communication error
between the workstation and the server. Using Etherreal, I've come
across a
TCP ack Lost segment error . The souce is the server and the
destination is the workstation. The error repeats a few times before
the server name is put into the bad server cache, and thus the mapping

I researched and think the error is caused by network congestion, or
perhaps slow response on the workstation side. There are settings on
the server to tune the TCP but I am not sure which I should change.
This is an intermittent error, but it happens enough to cause us

What exactly does this error mean? Why is it happening? What Novell
settings can I change to fix this without affecting our current system
too much.?