I've got quite the puzzle in front of me with using Art-Net output from Watchout. I'm using a pair of Elation Color Chorus 24 lights, set in a single universe, in the same network/subnet as my Watchout cluster. When I try to send an Art-Net signal from Watchout, the lights do not respond to the signal. When I use LightKey on a MacBook in the same subnet, the lights work fine. When I use an Art-Net to DMX converter with Watchout, the lights work fine.
I grabbed two ArtDMX packets, one from Watchout, and the other from LightKey, to see what they do differently. Both are broadcasted ArtDMX packets, which are practically identical, apart from two differences. Below is a screenshot from the LightKey packet for reference. As you can see LightKey sends a Sequence byte, containing information about where it is in its sequence. It also sends data for a full DMX universes, 512 adresses, even if only 8 adresses are being used.
The Watchout packets don't use a Sequence byte (value is always 0), and only sends adresses that are defined in the Watchout Project's outputs. So instead of sending 512 adresses, it only sends, for example, the 8 adresses I have defined in my outputs. Could it be that my lights need this extra data to even acknowledge the signal being sent?