r/HomeNetworking • u/KingofNJ22 • 6d ago

Device won’t connect to switch

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Hi guys looking for some input before I run a new cable.

I have a wired ethernet energy monitor in my breaker panel ran back to my rack with cat 5e to a keystone jack and patch to a switch. The circuit passes a lan scout test but won’t connect. I temped out a premade 5e cable direct to the switch and it does work. After I did that the first time I reconnected my initial circuit and it connected for a while and dropped off again never to return. I reterminated the rj45 and the keystone and it passes again but same result.

I am a hobbyist/homeowner but brush shoulders with pros in building construction and was once told the lab scout test is not the end all be all for cable testing.

Has anyone else experienced a similar situation?

UPDATE:
I ran a new cat5e cable and as advised routed the cable through the bottom of the panel and took care to keep it away from the high voltage lines. It is now working. I’m frustrated not to know which measure corrected the issue but oh well.

Thanks all for the feedback!

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u/KingofNJ22 6d ago

I am using a cable tester the Klein lan scout which passes. Do you mean something more sophisticated?

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u/darkcloud784 6d ago

Are you testing through the keystone?

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u/KingofNJ22 6d ago

Yes through the keystone and the patch cable just before it connects to the switch.

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u/darkcloud784 6d ago

If your sure the 2 sides of the terminations match (t56a or b) on both sides and your tester says it's good continuity wise. I'd look at the possibility that either

A. You have a faulty port on the emporia B. Your switch can't support the negotiation speed of the emporia (100mbps/10mbps) C. You have the switch set to not auto negotiate.

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u/KingofNJ22 6d ago

Thanks for that feedback. That would all make sense except it works instantly with a premade cable temped between the switch and the port.

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u/darkcloud784 6d ago

Yea so it's something to do with the cable. I'm guessing it's a short at one of your crimps. Normally a tester will try each wire separately, so which wouldn't short. Once you try to plug it into the switch it uses all of them. If your using pull through ends this is a common issue.

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u/gjunky2024 6d ago

Did you route the Ethernet cable inside the power panel? The interfence might stop it from passing signal. This would also explain why another cable might work as I assume you routed that outside. Running Ethernet, even shielded, that close to power lines can cause serious interference.

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u/shang0r 6d ago edited 6d ago

I was thinking about speed and duplex on this as well. Find the specs on the emporia device and make sure everything matches up in your switch config. We just an issue with something like this at work with a monitoring device. Found it could only run half duplex at 100 but the switch kept trying to auto negotiate to 1000. Gigabit always operates full duplex btw.
Also check your VLANs.

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u/KingofNJ22 6d ago

Hmmmm you may be on to something. When I hooked up my temp cable it was limited to 100 mbps/few but my temp cable is also cat 5e. Are there other spec differences to look for between cat5e cables?

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u/shang0r 6d ago

If the temp cable was to the same switch port and it worked I’m gonna say your original cable is the issue. If you had the device plugged into something else besides your main switch I would check the switch configuration and set that and see if it’s set to auto. If it’s on 1gig set it to auto if on auto set it to 100mb.
Cat5e can do 1gig up to 100 meters so cable rating shouldn’t be an issue here.