There are some TCP settings you can change, although I have been told
that this is more of an art than a science, and messing this up can make
your system behave surrealistically ;-) . IOW, do this at your own risk.
This isn't on a production HP 3000, is it?

We are struggling with some TCP questions ourselves, and I for one hope
that others can shed some light on tuning these settings.

Run NMMGR.
hit F1: Open Config
hit F2: NS
hit F2: Unguided Config (at this point, you will get 'pseudo-buttons')
hit F1: Go To Netxport
hit F2: Go To GPROT
hit F2: Go To TCP
Make your changes here. You can use F7: help, or, better, read the
manual.
If you are not comfortable with your changes, hit F8: Prior Screen and
start over. I cannot remember if it is necessary to hit F6: Save Data,
and am unwilling to try it and see.
hit F8: Prior Screen to get back to the "#2  Main"
hit F5: Utility
hit F3: Go To VALIDATE
hit F1: Validate NETXPORT
hit F8: Prior Screen
hit F8 to exit
These settings take effect next time NS are restarted.