I have managed to do this without problems on other distros. I have set IP address/gateway/dns in the box (which is a linux base vu+ duo)
In "add network interface" I choose ethernet and enter the Ipaddress, gateway etc to match those of the box. In other distros I can set the connection method to "shared , or shared with other computers, rather than DHCP. I am not given a similar option here.
Unfortunalely, network centre seems to assume I want to use this setup to connect to the internet, which is obviously not possible.
A side-effect of this is that it tries to use this new setup as a default internet connection and therefore, disconnects my ppp0 connection.
I therefore have to fiddle around with with the network connections, including unticking the ethernet box in the active connections, in order to get my internet connection back on ppp0.
Should I be trying to connect this box in a different way?
Is the network centre only for connection to the internet?