Difficulty using old setup of lan1741 with net5501 with new high current power supply

Dear soekris-tech readers,

I am not able to use any of the ethernet ports on the lan1741 connected to my
net5501-70 board, e.g. to get an address using dhclient. The leds are not
active either, compared to the leds of the four local vr(4) based ports. 

I have installed OpenBSD on a CF card on the net5501. The ports of the
lan1741 is discovered at boot. Though it looks sane to me, perhaps someone
would find it useful comparing dmesg output from a working vr(4) based
embedded NIC with a non-working sis(4) interface. Either way, here are some
(possibly) useful output with mac addresses omitted:

  $ dmesg | grep vr2
  vr2 at pci0 dev 8 function 0 "VIA VT6105M RhineIII" rev 0x96: irq 9, address [...]
  ukphy2 at vr2 phy 1: Generic IEEE 802.3u media interface, rev. 3: OUI 0x004063, model 0x0034

  $ dmesg | grep sis2
  sis2 at pci1 dev 2 function 0 "NS DP83815 10/100" rev 0x00, DP83816A: irq 10, address [...]
  nsphyter2 at sis2 phy 0: DP83815 10/100 PHY, rev. 1

I am able to use dhclient with vr2, for sis2 the leds are not active and I
can not get an address. 

The original power adapter that I ordered with the device stopped working
some time ago, and I started using another adapter today:

  http://www.dx.com/p/100w-universal-ac-power-adapter-for-laptop-with-8-adapters-ac-110-240v-dc-12-24v-33874

The old adapter was labeled `DC 12V 3A.' The new adapter has variable
voltage, and is labeled `100W. DC 15-20V max 5A, 22-24V max 4A.' The adapter
also has a 12V step. From electromagnetism we know the Rate of Potential
Energy Loss to be P=IV, where V is in volts, I is in amperes and P is in
watts. Thus, on the 12V step we would get I = (20V * 5A) / 12V ==> I = 8A.
Since 8A > 3A, in theory there should not be a problem using the new
adapter. 

Do any of you have suggestions as to how to get the sis(4) interface up and
running?

-- 
Rasmus Liland, jrl at jrl.dyndns.dk, jens.rasmus.liland at nmbu.no