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An Ethernet light usually tells you whether a port has a link and whether data is moving; on some devices, its color also indicates the negotiated link speed or another port state. There is no universal color code. Check the manual for the exact router, switch, or computer model before treating amber, blinking, or darkness as a fault.
What Ethernet lights usually indicate
Read the light in context: first note whether it is off, steady, or blinking; then check its color and the device’s LED mode. A steady light often indicates a link, while blinking often indicates traffic, but these are common patterns, not universal rules.
- Off: Often means no link or no connected device. A managed switch port may instead be disabled.
- Steady: Often means a link is established. Depending on the device, color may also report speed or status.
- Blinking: Often means data is being sent or received. Blinking alone does not necessarily mean a problem.
These interpretations vary by model and, on some switches, by the selected LED mode. The examples below are specific to the manufacturers and devices named.
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Examples from router and switch manuals
| Device and scope | Off | Steady light | Blinking or color detail |
|---|---|---|---|
| NETGEAR routers covered by NETGEAR’s guide | No device connected to the Ethernet port | A powered device is connected | Blinking means sending or receiving traffic. White or green indicates 1 Gbps; amber indicates 100 or 10 Mbps. These meanings apply to the models listed in the NETGEAR router guide, not all routers. |
| TP-Link Wi-Fi 5 and Wi-Fi 6 router examples | No powered device connected | A powered device is connected, with no traffic | Green flashing indicates LAN activity. TP-Link says its guide applies to most models, with differences; consult the specific router manual. |
| NETGEAR GS324 switch | The speed LED is off when there is no link | Green indicates 1000 Mbps; yellow indicates 10/100 Mbps | The LED blinks when network traffic passes through the port. See the GS324 FAQ for this model-specific behavior. |
| Cisco Catalyst 2960 switch in STAT mode | No link or the port is administratively shut down | Green indicates a link | Blinking green indicates activity; amber indicates spanning-tree blocking; alternating green and amber indicates a link fault. In SPEED mode, colors indicate speed instead. Consult the Catalyst 2960 hardware guide. |
Why amber or yellow does not always mean a fault
On the NETGEAR router models covered by its guide, amber indicates a 100 or 10 Mbps link, rather than a fault. NETGEAR Support’s guide, last updated July 7, 2025, states: “The LED color indicates the speed: white or green for Gigabit Ethernet (1 Gbps) connections, and amber for 100 Mbps or 10 Mbps Ethernet connections.” That description applies to the listed NETGEAR models, not to Ethernet ports generally. On a NETGEAR GS324, yellow indicates 10/100 Mbps. By contrast, a Cisco Catalyst 2960 in STAT mode uses amber for spanning-tree blocking and alternating green/amber for a link fault.
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Color can therefore describe link speed on one device and a switch state on another. Check the model and, if applicable, the selected port LED mode before interpreting it.
How to check a dark or unexpected Ethernet light
- Identify the device and exact model. Find its Ethernet LED definitions in the manual or official support page. For a managed switch, check the current port LED mode; on the Catalyst 2960, STAT and SPEED modes assign different meanings to colors.
- Check both ends of the connection. Confirm the far-end device is powered, the cable is seated at both ends, and it is plugged into the intended ports.
- Check whether the port is enabled. A dark switch port can have no link or be administratively shut down.
- Test with a known-good cable if the link is absent or intermittent. If available, try another port as a diagnostic. Cisco specifies Category 5 or higher cable for the copper Ethernet connections in its cited guide. Replacing a cable is not automatically necessary, and a cable test cannot rule out a disabled interface, failed port, configuration issue, or problem with the other device.
- Verify any speed indication separately. A light that indicates link rate is not reporting your internet service speed. Check the connected device’s network status or management interface to confirm the negotiated rate.
If the light is on a computer
Computer network-interface lights are also model-specific. The router and switch examples above do not establish a universal code for a PC’s Ethernet port. Check the computer or motherboard manual for that port’s color and blink definitions.
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