Somehow NM is convinced that it should try an Ethernet connection
first. You need a way to disabuse it of that notion.
Not necessarily. My netbook (stretch with NM) normally uses wires, and
that is the priority. I occasionally use wifi at home, and usually when
out, and use sleep quite often. When I open the lid, and tap a key to
wake the display, the wifi strength signal is already there.
[...]
I don't have an answer to the problem, but disabling Ethernet priority
with NM is not it.
Indeed, now that I think about it, when I have wired-ethernet connected,
I think both the wired and the wifi connections are setup, so the
priority is presumably doing something else.
Stefan