WIZnet WIZ550io

Oh dear. All sorts of oddities ...

On a high proportion of occasions now when I issue eth.setIP() I see a single DHCP_DISCOVER message, and then a few seconds later the USB connection to the Espruino drops (COM port gone, warble from computer). Tried on a couple of different boards. Repeatable. Strange ! Began to suspect USB cable, but happens on several different ones.

On some (rare) occasions I get a successful DHCP round trip

 _____                 _ 
|   __|___ ___ ___ _ _|_|___ ___ 
|   __|_ -| . |  _| | | |   | . |
|_____|___|  _|_| |___|_|_|_|___|
          |_| http://espruino.com
 1v61 Copyright 2014 G.Williams
>echo(0);
=undefined
>eth.setIP()
> Send DHCP_DISCOVER
> Receive DHCP_OFFER
> Send DHCP_Request
> Receive DHCP_ACK
=true
>eth.getIP()
={
      "ip":"192.168.254.194",
      "subnet":"255.255.255.0",
      "gateway":"192.168.254.100",
      "dns":"208.67.222.222",
      "mac":"000000000101"
    }
> 

but a strange mac address (ending 01:01)

In fact, I have wireshark running to monitor what I think is the correct mac address (00:08:dc:1d:4c:33) and there is no DHCP to be seen. Is it all happening on that 01:01 address ??

Stuck again. Any ideas?