Frequently Asked Question
Why is the Ethernet light off or intermittent on my Mercusys desktop switch?
QUICK ANSWER
Start with power, the cable and the connected device. A dark Ethernet LED means there is no established link on that port; it does not by itself identify a failed switch.
Applies to: Mercusys unmanaged SOHO switches with a powered endpoint connected by Ethernet.
Work through these checks
- Check the switch power indicator and use the correct power adapter. Confirm that the endpoint is awake and its Ethernet interface is enabled; a sleeping device may change the port indication.
- Replace the connection with a short known-good patch cable. Bypass wall outlets, couplers and extensions for this comparison, then inspect them separately if the short cable works.
- Try the same working endpoint and cable on another switch port. Then try another endpoint on the suspect port. Record whether the fault follows the cable, endpoint or one port.
- On a computer, leave Speed & Duplex on Auto Negotiation unless the network administrator has a documented requirement. If an established link repeatedly drops, record the times and test another compatible adapter or port.
Confirm the result
The port should establish a stable link and pass a sustained local transfer without reconnecting. An illuminated LED confirms a link, not successful DHCP or internet access.
Before going further: Do not connect two live switch ports together to test them; that can create a network loop. Keep the production network out of bench tests.
If you need help
Include these details in your ticket: Switch model/version, power adapter rating, affected ports, endpoint model and the one-cable/one-endpoint comparison results.
Updated 261107