I think you need to go back to basics - and simplify your non-artnet control network... Its never a good idea connecting to the internet with show macs.

Catalyst listens to the 1st network adaptor available as defined by network preferences.
You can set the service order manually - but there is no way of locking catalyst to a particular network port (unless you turn all the rest off) Its an OS issue.

I guess you are doing this already - but for others who are reading:
Catalsyt doesnt actually have to be on a 2.x.x.x address to receive artnet (just so long as one of the network ports is set up in this range) This is how you can split artnet from Sync ID and 'control' if the other network port is set to a non-artnet IP address (192.x.x.x)

S