Acutis Ethernet not working: how to fix it
You plugged in a cable expecting a fast, stable link and got nothing, or worse, a connection slower than the Wi-Fi you were trying to escape. Wired networking has fewer moving parts than Wi-Fi, which is good news: there are only a handful of things to check, and you can isolate the fault quickly.
Ethernet not working: start at the physical layer
When Ethernet is not working at all, the first suspects are the cable and the port. Before touching any settings:
- Look at the port lights. Most Ethernet ports have a small LED that lights or blinks when a link is established. No light usually means no physical link: bad cable, bad port, or the other end is off.
- Reseat both ends. Unplug and firmly re-click the cable into the computer and the router or switch. Listen for the click.
- Swap the cable. Cables fail silently, especially where they bend at the connector. Try a known-good cable.
- Try a different port on the router or switch. Individual ports do die.
If a different cable in a different port lights up and works, you have found a dead cable or a dead port and you are done.
Check that the operating system sees the connection
If the link light is on but you still have no internet, check what the computer thinks is happening.
Windows: open Command Prompt and run ipconfig /all. Look for your Ethernet adapter. If it shows an IP address starting with 169.254, the adapter never got an address from the router (a DHCP failure). If it shows "Media disconnected," the OS sees no link at all.
macOS: open Terminal and run ifconfig en0 (the wired adapter is often en0 or en1). An inet line with a real address means it connected.
A quick reset of the address often helps: on Windows run ipconfig /release then ipconfig /renew.
The driver
If the hardware looks fine but Windows shows the adapter with a warning, the network driver may be missing or corrupt. Open Device Manager, expand Network adapters, and look for your Ethernet controller. A yellow triangle means a driver problem. Right-click and choose Update driver, or uninstall it and reboot so Windows reinstalls it. After a major OS update, reinstalling the manufacturer's driver from their site sometimes restores a port that quietly stopped working.
Ethernet slower than Wi-Fi: the duplex and speed mismatch
If Ethernet connects but is bizarrely slow, the usual culprit is a link speed or duplex mismatch. A gigabit port that negotiates down to 100 Mbps, or worse to "half duplex," will crawl.
- Check the negotiated speed. On Windows, in the adapter's Status window, look at the Speed field. If it says 100 Mbps on gigabit gear, something forced it down.
- The cable is the most common cause. A damaged cable, or an old Cat 5 cable, can limit you to 100 Mbps. Use a Cat 5e or Cat 6 cable for gigabit.
- Leave duplex on auto. In the adapter's Advanced settings there is a "Speed & Duplex" option. It should be set to Auto Negotiation. A hard-coded setting that disagrees with the switch causes a duplex mismatch and terrible throughput.
Is the NIC dead?
If the same cable and port work fine for another device but never for this computer, the network card (NIC) in this machine may have failed. Confirm it:
- Plug a laptop you know works into the same cable and port. If it connects, the wiring is fine.
- Back on the problem machine, if no cable, no port, and a driver reinstall change anything, the onboard NIC is the likely failure.
A dead onboard NIC is not the end. A USB-to-Ethernet adapter or a PCIe network card is a cheap, reliable replacement.
A clean order to test in
- Link light on? If not, swap cable and port.
- Does the OS show an IP? If it shows
169.254, release and renew. - Driver healthy in Device Manager? Reinstall if not.
- Connected but slow? Check negotiated speed and cable category, leave duplex on auto.
- Works for other devices but not this one? Suspect the NIC.
🧰 The gear for this
Swap in a known-good cable and confirm the run with a cable tester before you blame the NIC. See our network troubleshooting toolkit for cable testers, quality Cat 6 cables, and USB-Ethernet adapters, from bargain to pro.
Stop guessing — is it the network or your machine?
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Get Acutis Go — freeFrequently asked questions
Why is my Ethernet not working but WiFi is fine?
Wired links have fewer moving parts, so when they fail the cause is usually physical or driver-level rather than a network problem: a cable that has been crushed or half-seated, a dead switch port, a disabled adapter, or a driver that needs updating. The fact Wi-Fi works tells you the router and internet are fine, which narrows it to that wired path.
What do the lights on the Ethernet port mean?
The link light tells you the two ends have negotiated a connection at the physical layer. No light usually means no usable link - the cable, the port, or the adapter. A light with no traffic points further up the stack, at addressing or configuration rather than the cable itself.
Why is my Ethernet slower than my WiFi?
That is the classic sign of a speed or duplex mismatch, where the two ends have not negotiated the link properly and have fallen back to something far slower. It can also be a damaged cable that still passes a link but at a lower rate. Both are worth checking before assuming the adapter is failing.
How do I know if my network card is dead?
Rule out the cheap things first: try a known-good cable, a different port, and check whether the operating system still lists the adapter at all. If the adapter is missing from the system, or shows an error even after a driver reinstall, then the hardware is the likely suspect - but it is rarely the first thing at fault.