Member Avatar for gortonsfi

A couple weeks ago my Netgear router bit the dust. I consoled myself with a new Linksys 802.11 g router :)

I found that both the Internet port and the the UTP cable are both dead. I thought it was just the port but when I tried to use the cable for another purpose it was useless. I retested the old router and the internet port is definitely bad. I had noticed minor symptoms for the last few months, but not bad enough to try to track down.

Is this just a coincidence? What could cause both the port and the cable to go bad at the same time?

Thanks,
Jeff

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Dani AI

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For : simultaneous failure of an Ethernet port and the patch cable is rarely pure coincidence. and have seen the same class of problem — the practical takeaway is that energy on the copper (surge, stray mains voltage, or a ground-potential fault) or a wiring short is the usual culprit. The following diagnostic checklist and protection notes give concrete, low-cost steps to confirm the cause and reduce recurrence.

Recommended diagnostic checklist

  • Power down and isolate the suspect cable before testing. Any visible burn, melted plastic, or a strong electrical smell means the cable should not be plugged into another device.
  • Visual inspection: check the RJ-45 plug and jack for scorch marks, bent pins or melted insulation.
  • Basic cable test (multimeter): with both ends disconnected, set the meter to continuity/ohms and verify each pin maps end-to-end (1→1, 2→2, etc.). Good pairs show very low resistance; intermittent or open readings indicate a damaged cable.
  • Swap test: use a known-good patch cable on the same router port and test a known-good switch or NIC on the other end. If the router port still shows no link lights while other ports work, the router port is likely damaged. If a replacement router/switch is available, try the suspect cable there to confirm the cable is dead.
  • Check in-wall wiring and any pass-through equipment (KVMs, surge strips, PoE injectors). Failures often propagate through intermediate gear.

Protection and next steps

  • Replace any damaged cable; reterminate only after confirming all pairs test OK. For wall runs, use a professional cable tester (pair length/attenuation).
  • Add proper surge protection and grounding for both AC mains and data lines (data-line protectors or fiber isolation for critical links). For PoE devices use inline PoE-rated protectors.
  • If multiple devices failed at the same time, consider warranty/RMA and document damage (photos); insurance may cover lightning/mains events.

These steps prioritize safety and isolation first, then simple tests to separate a bad cable from a bad port.

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Member Avatar for dazed_confused

Hi there,

I had something happen just like that today with a Belkin, except it took out the onboard ethernet controller too!!! I was at a loss for a few minutes to think that all three were bad.

dazed_confused

Member Avatar for Justin01

I work at a medium sized radio station up here in New Hampshire and we just suffered a lightning struck a few weeks ago. Besides losing a half dozen $300 kvm extenders, we also lost several switches along with a few NIC's. Now the interesting thing was that the switches that got blown out wern't totally dead. In regards to the one 15 port switch we had, the lightning killed about half the ports. The rest were fine.

In regards to the kvm extenders, the lightning go to them through the cat 5. In this case it would have paid off to have some cat 5 surge protectors hooked up.

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