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How to test ethernet switch?



I hooked up a simple Netgear switch to allow me to run lines to each of my optic boxes and to wifi boosters.  When I turned it all on my whole system when down - no wifi, no tv - nothing - wife not happy 😉 - but when I disconnected the switch all came back on - thankfully.  


I tested the ethernet lines with a handheld gizmo that you hook to each end and watch the lights.  Can I use this to test if the signal is running through the switch?  It doesn't.


Thanks for the help



I don't have a computer that has an ethernet port to test that way.  

What model is the Netgear switch?


Get a USB Ethernet dongle for your laptops. They are cheap and it comes in handy. I use it when I need to download OS updates or need reliable video calls.


The testing device you descibe sounds like a cable tester. Do not connect it to your network. It's meant to test cables in isolation. Use it to verify each cable is good.

Its a NETGEAR 8 Port Unmanaged Switch (GS208).  


I was hoping that the signal that the cable tester puts out would be able to test the switch too - guess not. 


I'll get an adapter so I can test it with my laptop - until then though is there another way to test it?



There isn't any setup you need to do for an unmanaged switch other than plug in the power. I suggest you connect one device at a time to the switch starting with the router. Check the the link light on the port each time.


Just for clarity, do you have fibre? If so, did you connect the ONT to the switch or is it running from your modem to the switch then out?

Community Power User
Community Power User

What port and router are you connecting the switch to?


This may be useful:



Just a long time customer hoping to help.


I had the switch connected to the router.  I'll try connecting the router line and then the others one at a time.  I was using port #1 for the router.

Should I be seeing a solid green light as I hook up each line?  Will it matter if there is anything connected at the other end of the line?


If the switch is Ok - any idea why my first attempt sent everything into chaos? At that time the lights on the switch were blinking like crazy.   

I do have fiber.


Community Power User
Community Power User

Strange. I have multiple switches in my home network, including a Netgear GS208. I've never had any issues with mine. Connecting it to port 1 on the Actiontec is fine. Normally if the device you are plugging in to the switch has power, the green lights usually should light up - solid or flickering. Flickering shows there is activity on the network/connection. If nothing is plugged into the other end of the ethernet cable, there will be no light on the switch.


As @xray  mentioned, try plugging one device at a time into the switch to see which could be the problem.

If you find a post useful, please give the author a "Like" or mark as an accepted solution if it solves your trouble. 🙂

I tried the switch again.  Connected to the router first and then each wire one by one.  All of the wires except one had nothing on the other end.  The other was connected to an Optik box.  The Tv stated Ok but then soon started to pause and then stopped with the message "internet signal lost".  I tested all of the cables - all seem Ok.  Bad switch?

Community Power User
Community Power User

A bad switch is rare but not impossible.

If you find a post useful, please give the author a "Like" or mark as an accepted solution if it solves your trouble. 🙂

It seems like it was sending some signal - at least for a while.  I ordered a dongle to try it with my laptop.  What do I look for?  How do I test it?

Just get another switch?


Connecting cables to the switch with nothing on the other end will do nothing. If the cables are good then it's the same and having nothing plugged in as far as the switch is concerned. The only time it would make difference is if the cable is shorted. It's best to do the test with just the cable to the router and the cable to the Optik box.


When you got the |Internet signal lost" message what was the state of the port LED lights on the switch (both to the Optik box and the router)?


Is the switch new or old? While it's possible the switch is bad it's more likely the power adapter might be bad. I've had to replace a power supply on my Asus switch because it was buzzing. While it still worked at the time any noise from an power adapter is a sign of impending failure.


The switch is brand new.  I didn't look to see what the lights said when the tv went out - I'll try again.

I didn't hear anything from the power supply.  

I tried again. Same thing. Tv stops getting signal. Both lights, were I have the cable to the tv and the one to the Optik box, both blink green.

It works fine when I bypass the switch and hook the Optik Ethernet directly to the modem.

I’ll try another switch.

I read that for some switches at least you need to restart the router after connecting.  True?

Perhaps for managed switches but I've never needed to do that for unmanaged switches.