The short answer
Look at the small lights on the Ethernet port. No light at all means the physical link is dead — cable, port or the other end. A steady light with no internet means the link is fine and the problem is the IP address or DNS, which is an entirely different fix.
Wired connections fail in a much narrower set of ways than Wi-Fi, which makes them far quicker to diagnose. The port lights split the problem in half before you touch a setting.
Reading the lights
- No lights — no physical link. The cable, one of the ports, or the device at the other end.
- Solid light, no flickering — link established but no traffic passing.
- Solid plus flickering — link established and data flowing. Your problem is further up: IP, DNS or the connection itself.
If there is no link light
Reseat both ends and listen for the click
Ethernet plugs have a locking tab that snaps audibly. A plug that is nearly home makes intermittent contact, and the retaining clip snaps off easily, which is the single most common cause of a cable that will not stay seated.
Swap the cable
Cables fail internally, particularly where they are bent around furniture or run under a door. Try a different cable before anything else. This is the most common single fault.
Try a different port on the router
Individual ports fail. Move to another one and see whether the light appears.
Test the cable on another device
A laptop that works on that cable proves the cable and the router port are fine, which points at the original device’s network adapter.
If the link light is on but there is still no internet
The physical layer is fine, so the problem is addressing. Work through:
- Check the IP address. On Windows, run ipconfig in a terminal. An address starting 169.254 means the device never received one from the router. On a Mac, System Settings, Network, Details.
- Renew the address. Run ipconfig /release then ipconfig /renew on Windows. On a Mac, use Renew DHCP Lease in the network details.
- Set DNS manually. Try 1.1.1.1 or 8.8.8.8. If pages load afterwards, your router’s DNS was the fault.
- Disable Wi-Fi entirely while testing, so you know which connection you are actually using. A device on both often prefers the wrong one.
- Check for a VPN or proxy left configured from another network.
Ping your router’s address, then ping 1.1.1.1, then ping a website name. If the router replies but 1.1.1.1 does not, the fault is upstream at your provider. If 1.1.1.1 replies but the website name fails, it is DNS. That three-step test locates almost any connection fault.
Speed rather than connection
If the connection works but is slow, check the negotiated link speed — on Windows it is in the adapter status. A gigabit connection reporting 100 Mbps usually means a damaged cable with broken pairs, or an older cable. Cat 5e and above handles gigabit; genuinely old Cat 5 may not.
Frequently asked questions
Why is my Ethernet slower than my Wi-Fi?
Almost always a damaged cable negotiating a lower speed, or an old port. Check the reported link speed — if it says 100 Mbps on gigabit hardware, replace the cable first.
What does an IP starting with 169.254 mean?
The device asked the router for an address and got no answer, so it assigned itself a fallback. Check the cable, the router’s DHCP settings, and whether the address pool is full.
Does Ethernet cable quality matter?
Beyond meeting the category you need, not much. Cat 5e handles gigabit comfortably over normal household distances. Very long runs and 2.5 gigabit or faster networks are where Cat 6 starts to matter.
Can I use Ethernet and Wi-Fi at the same time?
Yes, though the device picks one route for traffic, usually Ethernet. If you are troubleshooting, switch Wi-Fi off so you know which connection is actually carrying your traffic.
Look at the port lights first. They tell you in two seconds whether you are chasing a cable or a configuration.
