Intel® Ethernet Adapter Limited at 100 Mbps
Content Type: Troubleshooting | Article ID: 000091032 | Last Reviewed: 10/05/2022
The Intel® Adapter stopped working at 1000 Mbps, it is only working at 100 Mbps with Cat6 cable and 1000 Mbps switch
Follow these troubleshooting steps:
If the OS is Microsoft Windows*, check the Windows Auto-Tuning settings
To disable Windows* AutoTuning, run the following command:
netsh int tcp set global autotuninglevel=disabled
To enable Windows* AutoTuning, run the following command:
netsh int tcp set global autotuninglevel=normal
Multiple customers confirmed that changing this setting has overwritten a speed limiting bug. If two systems are available, set the global autotuning level on the first one to disabled and on the second one to normal. For more details contact Microsoft* support.
Set the Gigabit Adapter connection setting to Auto Negotiation. This option is under the Advanced tab of the adapter’s properties, in Speed & Duplex – right-click the adapter and choose properties, click the Advanced tab, and click Speed & Duplex, and make sure it is set to Auto Negotiation. This should be the default setting.
If the issue persists, contact Intel Customer Support for assistance.
We have had reports of some ISP technicians telling their customers that a Gigabit option will appear in this setting if the network adapter is working correctly. This is incorrect. Auto Negotiation is the correct setting for Gigabit speeds in Speed & Duplex for Intel Networking Adapters. There is no option for 1.0 Gbps Full Duplex with some Ethernet drivers. Auto Negotiation will give a 1.0 Gbps link speed, provided your other networking equipment auto-negotiates correctly.