On my P55m-UD2 V1.1 board the integrated RTL8111D NIC is stable, but during booting it switches back to 100mbit - regardless what I've set the NIC manually before.
If I manually set the NIC to manual / 1000BaseT / full duplex etc. in the advanced settings this works - until the next boot. Then I can see the green LED changing to yellow on my GB-Switch during the boot process.
=> settings to 1Gbit are stored even the system is off (switch LED is green). During the boot process something...
solved: RTL8111D / RealtekR1000SL.kext switches to 100mbit
If I manually set the NIC to manual / 1000BaseT / full duplex etc. in the advanced settings this works - until the next boot. Then I can see the green LED changing to yellow on my GB-Switch during the boot process.
=> settings to 1Gbit are stored even the system is off (switch LED is green). During the boot process something...
solved: RTL8111D / RealtekR1000SL.kext switches to 100mbit