Q Light Controller+

QLC+ is running on the host at 192.168.4.1, sending on universe 1 to ArtNet Universe 0 with transmission mode at FULL (not sure what that means.)

Here's the part that's confusing.

The ODE MKII Ethernet to DMX converter is attached to the switch and has been assigned the address 192.168.7.1. We're on a 255.255.240.0 subnet mask so we have 192.168.0.XXX - 192.168.15.XXX.

In the ArtNET Plugin settings, the IP address, which was apparently automatically picked up, is 192.168.15.255, the last IP address on the entire network.

The lights respond...everything works...without explicitly setting the IP to 192.168.7.1 (the ODE MKII).

Is QLC+ broadcasting to the entire network, or is it supposed to be only sending to one IP address?

transmission mode full means : it will send all 512 channels of the universe even if they are not used

You have 2 ways (actually 3) how ArtNET is sent: unicast (to only one listener) or broadcast (all listeners in the pool of addresses will get it (even if the info is not for them))
In broadcast mode the typical used address is the last one in the range: so here the 255 one

and why am I using the term 'listener' because ArtNET is sent by UDP packets which by design aren't confirmed. You lose a packet - to bad, nobody will know.

(the third is multicast but out of scope here)

I personally prefer unicast because:
* it's clearer to understand: (from A to B)
* it won't be filtered by intelligent switches (managed ones) - they tend to filter broadcast storms and ArtNET is a broadcast storm. So no juice! If using switches (routers) the simplest ones win big.
* multiple senders using the same 'cable' in broadcast mode: a no-no to debug (unless you filter by sending address)