I fased with trouble when copy file to imx6 device by scp in gigabit network. It continously prints in terminal "fec 2188000.ethernet eth0: rcv is not +last" and disappear from network. And it may hapene after some time suddenly.
Transmitting files from imx6 at 1Gbit works fine. In 100Mbit receive and transmit works stable.
imx6d, pop package, phy AR8035, kernel fsl 4.9.88