Ethernet Not Working: How to Fix It

Diagnose First: Is It the Cable, Router, or Device?

Before trying fixes, spend 2 minutes isolating where the problem is:

1. Try a different device. Connect the same Ethernet cable to a different computer or device. If it works there, the problem is with your original device, not the cable or router.
2. Try a different cable. Borrow or use a spare Ethernet cable. If the new cable works, your original cable is faulty.
3. Try a different router port. Plug into a different LAN port on the back of your router. If that works, the original port is bad.
4. Check the router lights. There should be a solid or blinking light on the router's LAN port when a device is connected. No light = no physical link detected.

Fix 1: Restart Your Network Hardware

Power-cycle your modem and router in sequence:

1. Unplug the modem's power cable.
2. Unplug the router's power cable.
3. Wait 30 seconds.
4. Plug the modem back in and wait 60 seconds for it to fully connect.
5. Plug the router back in and wait 60 seconds.
6. Reconnect your Ethernet cable and test.

Fix 2: Release and Renew Your IP Address

If the cable shows "Connected" but there's no internet, your device may have a stale or invalid IP assignment:

Windows: Open Command Prompt as administrator and run:

ipconfig /release
ipconfig /renew

macOS: Go to System Settings → Network → select your Ethernet adapter → Details → TCP/IP tab → click "Renew DHCP Lease."

If your IP address starts with 169.254.x.x after renewing, DHCP failed — the router isn't assigning addresses. Restart the router and try again.

Fix 3: Update or Reinstall the Network Adapter Driver (Windows)

1. Right-click Start → Device Manager.
2. Expand "Network Adapters" and look for your Ethernet adapter.
3. If there's a yellow warning icon, right-click the adapter and choose "Update driver" → "Search automatically."
4. If updating doesn't help, right-click → "Uninstall device" → restart your PC. Windows will reinstall the driver automatically on reboot.

Fix 4: Disable Power Management on the Adapter (Windows)

Windows sometimes puts network adapters into sleep mode to save power, causing them to drop connections:

1. Device Manager → Network Adapters → right-click your Ethernet adapter → Properties.
2. Click the "Power Management" tab.
3. Uncheck "Allow the computer to turn off this device to save power."
4. Click OK and reconnect.

Fix 5: Reset Network Stack (Windows)

If nothing else works, a full network stack reset resolves most software-level Ethernet issues:

netsh int ip reset
netsh winsock reset
ipconfig /flushdns

Run these in Command Prompt as administrator, then restart your PC.

Fix 6: macOS — Create a New Network Location

1. System Settings → Network.
2. Click the "…" button → Locations → Edit Locations.
3. Add a new location, name it "Ethernet Fix," and switch to it.
4. This creates fresh network configuration — often resolves persistent macOS Ethernet issues.

When It's a Hardware Problem

If you've tried all the above and Ethernet still doesn't work on one specific device, the RJ45 port may be physically damaged (especially on laptops where the port bends from cable tension). A USB to Ethernet adapter ($15–25) is an inexpensive fix that bypasses the built-in port entirely.