"It's all in the wrist" (V White). You need to decide who is "hosting" the Network Stream (in my case, it's the PXI), and which direction you are streaming (I actually have 4 streams, one PC -> PXI and three PXI -> PC). The key step is that you need to be sure that the PXI (the system running the Network Stream "engine") is running first.
Note that the error you saw, -314004, (probably) means that the PXI is not, in fact, "listening" for the Host to make a connection. If you suspect there's a "race" condition (you accidently start the Host first), you can simply say "Oh, that error means I need to wait 10 seconds for the PXI to get ready, then try again".
If all else fails, you can get the PXI to restart itself, ensuring a clean system.