How to Fix Ethernet Not Working But Wi-Fi is Working

 If your Wi-Fi works and your Ethernet does not, you have already been handed the most useful diagnostic result available. Most of what could have gone wrong is now ruled out.

Your internet connection is fine. Your router is fine. DNS is resolving. DHCP is handing out addresses. The provider is not having an outage. None of that can be the problem, because wireless traffic passes through all of it successfully.

What remains is a short physical path and a small number of settings. Ethernet not working while wireless functions is one of the easier faults to isolate, provided you work through it in the right order.

Start at the Link Light

Before touching any software, look at two lights: the one on the computer's network port and the one on the switch, router, or wall socket at the other end.

• No light at either end. The physical connection has failed. The fault is the cable, a port, or the run between them.
• Light at the switch, none at the computer. Often a failing adapter or a partially damaged cable.
• Lights at both ends, steady. The physical layer is working. Move on to the software section below.
• Light flickering or cycling on and off repeatedly. A marginal connection, usually a damaged or poorly terminated cable.

This one observation splits the problem into two entirely separate investigations, so do it first.

The Cable Is the Most Likely Cause

Network cables fail more often than anything else in this chain, and they fail invisibly. The copper inside can break while the outer jacket looks perfect. Cables get crushed by chair wheels, pinched under desks, bent past their radius, and pulled out of their connectors gradually over years.

Test by substitution rather than by inspection:

• Swap in a different cable you know works.
• Try the suspect cable on a device you know is working.
• Check that the plastic retaining clip on each connector has not snapped. A broken clip means the plug sits loose, and the connection drops whenever the desk is bumped.
• Look at the length of the run. Beyond roughly 100 metres, Ethernet becomes unreliable regardless of cable quality.
• If the cable runs through a wall socket, remember that there are actually two cables — the patch lead on your desk and the permanent run to the patch panel. Either can fail.

Check the Port

Ports fail, and switches sometimes disable them deliberately.

Move the cable to a different port on the switch or router. If it works there, the original port is the problem — either physically failed or administratively shut down.

In a managed environment, several configurations can silently disable a port:

• Port security shuts a port down when it sees an unexpected MAC address. This commonly triggers when someone swaps a computer or plugs in a personal switch.
• Spanning tree places a port into a blocking state if it detects a potential loop. The link light is on and no traffic passes.
• 802.1X authentication blocks a port until the connected device authenticates successfully. An expired certificate or a machine that has left the domain will fail silently.
• The port is in the wrong VLAN, producing connectivity to a network that does not include your gateway.

If you are on a corporate network and the cable and port both appear fine, this is the point to contact whoever manages the switches.

The Windows Side: Adapter, Driver, Power

With the physical layer confirmed, turn to the operating system.

Is the adapter enabled? Open network connections by pressing Windows key plus R and running ncpa.cpl. A greyed-out Ethernet adapter has been disabled. Right-click and enable it.

Is the driver working? In Device Manager, look under Network adapters. A yellow warning triangle indicates a driver problem. Updating the driver from the computer manufacturer's support site is more reliable than letting Windows search automatically, which frequently reports that the best driver is already installed when it is not.

Is power management interfering? This causes a specific and frustrating symptom: the connection works, then drops after the machine has been idle or after waking from sleep. In Device Manager, open the adapter's properties, go to the Power Management tab, and clear the option allowing the computer to turn off the device to save power.

Has a recent update broken it? If the problem began immediately after a Windows update or a driver update, rolling back the driver is a reasonable next step.

What a 169.254 Address Means

Run ipconfig /all in a command prompt and look at the Ethernet adapter's IPv4 address.

If it begins with 169.254, the adapter asked for a DHCP address and received no reply. This is called automatic private addressing, and it is the operating system assigning itself a placeholder. The physical link is working — the machine successfully sent a request — but nothing answered it.

Causes, in order of likelihood:

• The port is in a VLAN with no DHCP service.
• The DHCP scope has run out of available addresses.
• A DHCP relay is misconfigured on that segment.
• The DHCP server is down, though wireless working suggests otherwise unless the two networks use different scopes.

Try ipconfig /release followed by ipconfig /renew to force a fresh request, and watch whether an address is granted.

If instead the adapter shows a normal-looking address but still fails, check that the subnet mask and default gateway are correct and that the gateway is in the same subnet as the address.

The Trap: Both Connected, Traffic on Wi-Fi

Here is the situation that generates the most confused reports, and it is not a fault at all.

When a Windows machine is connected by both cable and wireless simultaneously, it chooses one for outbound traffic based on interface metrics. Normally it prefers the wired connection. Occasionally — after a driver change, a VPN installation, or a manual adjustment — the metrics end up favouring wireless.

The user then reports that "Ethernet is not working," when in fact it is connected and simply not being used.

To check, run:

netsh interface ipv4 show interfaces

This lists each interface with its metric. Lower values are preferred. If the wireless adapter has a lower metric than Ethernet, that is your answer.

The clean test is to disable Wi-Fi entirely and see whether connectivity continues over the cable. If it does, nothing is broken — the routing preference simply needs adjusting, which can be done by setting the interface metric manually in the adapter's advanced TCP/IP properties.

When It Works But Is Slow

A related symptom worth covering: the connection functions but performs far worse than wireless, which should not happen.

The usual cause is a duplex or speed mismatch. Check the negotiated speed in the adapter status. A gigabit adapter reporting 100 Mbps, or worse 10 Mbps, indicates a negotiation problem — almost always a cable fault where some of the eight wires have failed, since lower speeds require fewer working pairs.

That is a genuinely useful diagnostic signal. A cable that negotiates at 100 Mbps instead of 1 Gbps is telling you it is damaged, even though it appears to work.

Leave both ends on automatic negotiation. Manually forcing speed and duplex is a common source of mismatches and is rarely necessary on modern equipment.

A Sequence That Works

1. Check both link lights. Physical or software, decided in five seconds.
2. Swap the cable for a known-good one.
3. Try a different port.
4. Run ipconfig /all and examine the address.
5. If 169.254, release and renew, then investigate DHCP.
6. Check the adapter is enabled in ncpa.cpl.
7. Check Device Manager for driver problems.
8. Disable power management on the adapter.
9. Check interface metrics if both connections are active.
10. Test the adapter on another network, or another device on this port, to isolate hardware.

If You Are Not on Windows

The logic is identical; the commands differ.

On macOS:

• Check the connection in System Settings under Network. A greyed or inactive Ethernet entry indicates the adapter is not connected or is disabled.
• Run ifconfig in Terminal to see the assigned address. A 169.254 address means the same thing here as on Windows.
• Use networksetup -listnetworkserviceorder to see the service priority, which is the macOS equivalent of interface metrics. Wired should normally sit above Wi-Fi.
• Renewing the address is available through the Details panel of the Ethernet connection.
• Many modern Macs have no built-in Ethernet port at all, so the adapter in question is a dongle — and dongles fail considerably more often than integrated ports.

On Linux:

• ip link shows whether the interface exists and whether it has carrier, which is the equivalent of a link light.
• ip addr shows the assigned address.
• sudo dhclient -v <interface> requests an address verbosely, showing exactly where the process fails.
• ethtool <interface> reports the negotiated speed and duplex, and whether a link is detected at all.
• dmesg | grep -i eth often reveals driver messages that explain a failure directly.

The diagnostic sequence remains the same regardless of platform: physical layer first, addressing second, preference and routing third.

Resetting the Network Stack

If everything above checks out and it still fails, resetting the Windows networking components is a reasonable step. From an administrator command prompt:

• netsh winsock reset
• netsh int ip reset
• ipconfig /flushdns

Then restart the machine. This clears corrupted configuration that accumulates over time, particularly on machines that have had several VPN clients or security products installed and removed.

When It Is the Adapter

If a known-good cable in a known-good port produces no link light, and the adapter is enabled with a healthy driver, the network interface itself has probably failed.

On a desktop this is easily solved with an inexpensive add-in card. On a laptop, a USB-to-Ethernet adapter is the practical answer and often performs perfectly well. Either costs less than an hour of further investigation.

That is the pragmatic endpoint of Ethernet not working as a problem: the fault is confined to a short path, the tests are quick, and if the hardware has genuinely died, replacing it is cheap.