Network speed is determined automatically if "auto-negotiate" is set.
NM Spec says if that is not set a speed and duplex should be provided.
The .ui file (presumably leftover frmo something) defaulted to a speed
of 0 with had the special text of "automatic". This isn't actually
automatic, but just an invalid value which
WiredConnectionWidget::isValid (I think correctly) won't accept
End result is a user can't save any other settings as this widget
reports itself as invalid.
BUG: 383505