I've been running cvs for about two years over a slow connection
with no problems. About 3-4 weeks ago it broke with :

 cvs [update aborted]: received broken pipe signal

I can cvs checkout and I can update specific targets, but when I
try to update an entire directory such as syssrc or pkgsrc, I always
get the above error since this started. I can delete the local cvs
directory, check it out again, and still get the broken pipe signal
when I try to update.

I use the exact same sequence of commands that I use on machines
connected via high-speed connections, which work fine.

What's the problem with low-speed connections that started a few
weeks ago?