It would be interesting to see what the link partner sees. What does
it think the I219-LM is advertising? Is it advertising 1000BaseT_Half?
i219 parts come with LSI PHY. 1000BASE-T half-duplex is not supported.
1000BASET half-duplex not advertised in IEEE 1000BASE-T Control Register 9.
That is the theory. But in practice? What does the link partner really
see? I've come across systems which get advertisement wrong. However,
in that case, i suspect it is the software above the PHY, not the PHY
itself which was wrong.
Andrew