Wired Ethernet that doesn't connect is usually one of three things: dead cable, dead wall port, or laptop adapter / driver fault.

1. Check the cable

Look at both ends. The plastic clip should be intact and the cable seated firmly with a click. Try unplugging and plugging back in.

If you have a known-good cable, swap. Cheap Cat5e cables fail more often than expected, especially after years of being yanked.

2. Check the wall port lights

Most office wall ports have indicator lights on the laptop side:

  • No lights at all — the port may be inactive or the cable is dead
  • Steady green or amber, no blink — link is up but no traffic
  • Blinking — data flowing, looks good

Try a different wall port nearby. If the new port works, the original is dead — note both port numbers for the ticket.

3. Confirm the adapter is enabled

Settings → Network & Internet → Ethernet. The adapter should show as Connected when you plug a working cable in.

If it says Disabled, click to enable. If it says Unidentified network, you have a link but no DHCP — see step 5.

4. USB-to-Ethernet adapters

If you're using a USB-C Ethernet adapter (common on thin laptops without a built-in port):

  • Unplug + replug the adapter
  • Try a different USB port
  • Check Device Manager → Network adapters — there should be a Realtek or similar USB-Ethernet entry; if it has a warning triangle, the driver needs updating

5. DHCP renewal

Same as [Wi-Fi connected but no internet](/kb/no-internet-but-wifi-connected):

ipconfig /release
ipconfig /renew

This often clears stuck Ethernet states.

6. Cable category

Older Cat5 cables max out at 100 Mbps. Modern Cat5e and Cat6 do 1 Gbps. If your laptop is connecting at 100 Mbps and you expected gig:

  • Check the cable label — it'll say Cat5, Cat5e, or Cat6
  • Replace Cat5 with Cat5e or better

7. Network adapter speed settings

In Device Manager → Network adapters → right-click your Ethernet → Properties → Advanced tab → Speed & Duplex. If set to "10 Mbps Half Duplex" or similar, set to Auto Negotiation.

Rarely needs changing, but VPN admins occasionally lock it.

8. Disable + enable as a brute-force fix

netsh interface set interface "Ethernet" admin=disable
netsh interface set interface "Ethernet" admin=enable

Run as administrator. Works in seconds; cleaner than rebooting.

When to ticket

Raise a ticket if:

  • Multiple cables and multiple ports all fail (your laptop's Ethernet port is dead, or the patch panel is)
  • Other users in the area can connect but you can't
  • The adapter is detected but DHCP never assigns an address

Include the wall port number/label, what you've swapped, and any error message verbatim.