I'm working quite often with watchout and artnet and I can understand that this can be very frustrating. Most of the pitfalls have been named already.
- You have to be online to send artnet from the production computer
- You shouldn't have more than one active network interface
- Your production computer need to have a network route to your artnet receiver. If you don't have a router and aren't a network pro that usually means that both devices have to be in the same network subnet (within a subnet network packets are transmitted without a router)
- Some artnet receivers are only listening to artnet traffic on ip range 2.x.x.x or 10.x.x.x. Some even fool you because you can set up a different administration ip adress and they still only listen to the specified artnet adresses. The most compatible range is 2.x.x.x with a netmask of 255.0.0.0
- Artnet is (most often still) a UDP broadcast protocol. So there is no destination IP, to select a receiver you need a network port number which is called universe number in artnet. That is a little tricky point because different devices generate the port number in different ways. In watchout the port number is the same as the universe number and it is entered as a decimal number. In other products you often find terms like network, subnet and universe which relate to the original artnet specification. They don't have to do with IP adresses, they are just the original artnet way of generating the port number and sometimes they have to be entered in hexadecimal notation. The easiest way is to set everything to the lowest possible value. As already mentioned this is the next pitfall as some devices start at 0 and some at 1. So be prepared to juggle a little bit with a +-1 offset.
- Make sure you only have one device transmitting a specific universe. If you are not sure start with only one transmitting device at all. If more than one device is transmitting to the same universe this can lead to an unpredictable result.
- Most artnetmeter and artnet test programs are not suited well to troubleshoot artnet problems because they just show the values of an artnet universe and don't give you underlying network information. If you are a little nerdy you can try Ethereal, if you prefer a higher level use Artnetominator.
Generally I would whish that the artnet got a few more options from Dataton. In my opinion it would help a lot if I could have more network interfaces and could chose one or more for the display control, one or more for artnet, one or more for remote tcp or udp control...