I must confess that I have messed with the settings, but I have set everything
back to default the best I can.

The default is that both WiFi and Ethernet are supposed to connect
automatically, but Ethernet has higher priority.

Now, what does ���Ethernet has higher priority��� mean? My expectation is that WiFi
should disconnect when I plug in the Ethernet cable. Instead, both are
connected.

This works, but isn't useful, as I get much better speed if I then manually
disconnect from WiFi.

This is with connection.autoconnect-priority set to the highest value (99) for
my Ethernet connection.