[Soekris] new net4801 + openbsd 3.8 + dhclient failure

[Tom Williams]

Problem:  cannot get dhcp address from ISP via cable mode. dhclient is
stuck in this sequence:
  DHCPDISCOVER on sis1 to 255.255.255.255 port 67 interval 2
  ip length 328 disagrees with bytes received 332.
  accepting packet with data after udp payload.
  DHCPDISCOVER on sis1 to 255.255.255.255 port 67 interval 5
  DHCPDISCOVER on sis1 to 255.255.255.255 port 67 interval 9
  ip length 328 disagrees with bytes received 332.
  accepting packet with data after udp payload.
  ip length 331 disagrees with bytes received 335.
  accepting packet with data after udp payload.
  ip length 331 disagrees with bytes received 335.
  accepting packet with data after udp payload.
  DHCPDISCOVER on sis1 to 255.255.255.255 port 67 interval 11
  ...
  No DHCPOFFERS received.
  No working leases in persistent database - sleeping.

Can anyone give me the magic incantation that makes this go away and
will let me get an IP address from my ISP?

Just got the net4801 yesterday and have had the OpenBSD cd's and a
laptop hd waiting for it (plan to create a CF image later but for now
just doing plain old install to hd). The OpenBSD install went okay
(after I figured out how to make my dhcpd service bootp type requests).

The only change I've made is:
  sysctl.conf:  net.inet.ip.forwarding=1

/etc/dhclient.conf has been renamed, just in case I messed that up so
should be running with defaults. 'pf' is not running. 'ntpd' is not
running. In fact the only things running according to 'ps' are:
  /sbin/init
  syslogd: [priv] (syslogd)
  syslogd -a /var/empty/dev/log
  inetd
  /usr/sbin/sshd
  sendmail: accepting connections (sendmail)
  cron
  -ksh (ksh)

I've also tried this on sis2 and get the same results.

If I move the utp cables back to my old pentium 200 running OpenBSD 3.6
(and NOT using sis ethernet chips) everything is fine.  sis0 is
connected to a linksys switch and sis1 is connected to the cable modem.
I've seen the stuff about short/long cables. Is that somehow connected
to this? Any pointers or help would be really appreciated... I'd like
to avoid putting the net4801 back in the box and sending it back to
Soekris... its alot prettier than my old p-200.