port-shark/57613: Abysmal network performance on shark

[herdware%sdf.org@localhost]

>Number:         57613
>Category:       port-shark
>Synopsis:       Abysmal network performance on shark
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-shark-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Sep 10 11:45:00 +0000 2023
>Originator:     Björn Johannesson
>Release:        10_BETA
>Organization:
>Environment:
NetBSD dnard.home.lan 10.0_BETA NetBSD 10.0_BETA (GENERIC) #1: Wed Sep  6 21:54:35 CEST 2023  herdware%regin.home.lan@localhost:/usr/obj/sys/arch/shark/compile/GENERIC shark
>Description:
Network performance is ABYSMAL on shark. Speed is often 1.5-5kbyte/s with frequent stalling when using programs like ftp. Tried playing a wav-file from a nfs-share and it hung, can't break out with ^C.

Trying to use nfs as root hangs after setting the hostname.
However. Booting in single user mode (root on nfs) and playing that same wav-file works which is strange.
>How-To-Repeat:
Use the builtin cs0 ethernet on a shark.
>Fix: