Question How do you figure out what device is the problem on Ethernet?

Sep 8, 2020
My Ethernet goes down in my living room. It's an old house, but I had to have Ethernet for streaming as wireless simply kills me. My network is fed by the router to a main switch in the basement, then three secondary switches from there in different parts of the house. Only the living room goes down, and of course it has the most devices. I tried new wires, upgraded the switch, tried leaving suspect devices disconnected and still no idea what it could be. The living room simply falls off the network sometimes for up to an hour each time. The other portions of the network including wireless stay up fine, but I can't figure out what device could be causing the issue.

Any ideas? Tools? Should I get a managed switch for logging purposes?

Thank you!
You would need a fairly fancy managed switch to be able to get any form of logging.

It all depends on what you mean. There is huge difference between the lights on the ethernet port go out and everything doesn't work and all the lights are still on but you can not actually use it.

Generally a cable type of issue the port going back to the main switch will go down but all the rest of the ports on your switch will be fine.

Not sure what to suggest since I can be many things. Most switches are pretty cheap so that maybe a first step to replace it and then you have a spare if it is not the problem.

If everything looks good but does not work then you are going to have to do very detailed testing. In particular you want to see if you can ping between different devices both on and off the affected switch. Watching the MAC address table in end devices may give you a clue to duplicate ip issues or if something is blocking ARP entries. Not sure it can be very complex until you start to eliminate stuff.
Reactions: tsiec
Sep 8, 2020
I suspect it's a device issue, but can't narrow it down so easily, and no I do not own any SONOS products. The crazy thing is that only this switch goes down, so I replaced the switch and all the wires because I wanted to remove the normal culprits (It also gave me the opportunity to buy nice new matching cables of appropriate lengths. Looks much nicer!). The issue I am facing as that sometimes it will happen multiple times per day and other times it will not happen for multiple days, so trying to disconnect the possible problem device to see if the network comes back up isn't an option.

I know it's not an IP issue, but I hadn't thought of seeing what devices I could ping. I will have to make note of the IPs of the connected devices and try that next time, thank you.

I do have an old managed HP ProCurve which is only 8 port, but no power adapter. Maybe I could relocate some of the devices to that switch and hope the problem device is one that I moved. Of course it's been years since I did any decent networking, so hopefully I can remember how to use the thing.


Jul 1, 2017
To my mind, you should just disconnect device per device and go from there, not muchj else too it, unless you have a smart switch, which can tell you what is going on on which port etc

Trail and error my friend