zoomkat,
Understood, but I'm not clear if this only applies once you add the PoE module, or if it remains true even without.
However, if you look at my original procedure, above, it still does not explain why, even with the Ethernet removed, I have to go through the upload process twice. Once with a failure to load, then the second is successful. This is VERY reproducible.
This does not occur with other simple example sketches, non Ethernet Sketches. However, I have not tested to see if Ethernet simple examples load the first time.
I can test that.
Even so, I'm not sure what is going on. Is it possible that something in my Sketch is causing the issue, even though I have absolutely no errors in the compile?