Try pinging the IP address of the Duet, both with the Duet powered up (should always succeed, with a round trip time of under a millisecond), and with the Duet powered down (should always fail).
That's an unusual IP address. What sort of network do you have? If you have a PC connected via USB, do you get any messages on it when you try to load the web interface?
Ping is fine it averages 3ms over a minute. Its nothing special just a non-standard subnet. I'm sure the Duet itself is fine I can see it in the DHCP table and connect from other devices just not on this machine. I will get a PCAP done and take a look to see if there's anything suspicious going on.