One of the Ports in Intel® Ethernet Controller X550-AT2 Embedded on ASRock Motherboard Is Not Working after Firmware Update

• One out of two ports of Intel® Ethernet Controller X550-AT2 is not usable after firmware update.
• There is no LED working on one of the 2 LAN Ports of X550-AT2 even on BIOS level. Both X550-AT2 ports are still detected within Operating System

Issue is that Debug Mode is enabled which results in the single port failure following the update. This mode is for engineering and debug work only and is not supported in normal operation or basically in manufacturing. ASRock might be shipping the motherboards in this configuration. The Debug Mode tells the Firmware onboard the X550 it is ok to make certain writes to the NVM it might normally. This would explain the behavior and it also correlates to the isolation to this one manufacturer.

Request warranty replacement from ASRock and share the aforementioned information with the Original Equipment Manufacturer (OEM).