Following on from my previous post re unreliable WiFi connections, I found that the problem was caused by calling DataWriter::write()too soon after creating the DataWriter. Because write()is non-blocking it returned immediately without doing anything. Also, because it is void, there is no error return code.
So the publishing app was not in fact sending anything, and I had no way of knowing.
It obviously needed more time to assemble its plumbing, so I put in a 2 second sleep, after which it worked.
