Netware 6.5 SP3 cluster with the following patches:
NW65SP# overlay CD used for in-place upgrade from Netware 6.0 SP5
NICI 2.6.7
Secupd 8
OS3a server patch
Cifs 22a
AFP 239

The servers in the cluster were upgraded yesterday and today once normal
production mac users starting using it - problems started. I haven't been
able to isolate what is causing the problem (large file copies etc)

As far as I know we haven't enabled any of the extended MAC support on the
volume as discussed in some resent posts. Is there a way to tell?

Macs are losing connection but NCP and CIFS are OK.
Try to migrate resource to another node hangs server.
No antivirus runing on clusters.

I have logged a support call, but since this is a production issue I can't
test too many things until the next weekend. For now I have down-graded
AFPTCP.NLM to the version that was in NW6.0 SP5 (version running before
the upgrade). This version has been working for months without issue.
I have 6 more hours before the next production shift starts are I will
soon know if the old version has any problems running on NW65.

Any suggestions greatly appreciated.