I have a 2 buildings about 25 metres apart and there is a cat5 ethernet cable encased in a pipe between the 2 buildings. Just suddenly the connection stopped working. If I test the cable with a Molex SLT3S connectivity tester I see all the pairs light up fine. But the interesting thing is that if I connect the cable into a network device such as a switch I don't see the connection light light up.

Can you suggest any tool to troubleshoot further? Any ideas on what could cause this? What should be my next steps?

  • Are you sure the switch ports are working? If so, your only option is to replace the cable.
    – Ron Trunk
    Commented Aug 9, 2023 at 16:03

1 Answer 1


Very often when a cable suddenly fails, the termination isn't good enough. Double check each side's termination, and if that doesn't help replace the cable.

If you haven't done so, make sure no small animals can enter the pipe - I've seen mice breeding in there.

Also, vertical cabling is fiber by standard, so you might want to consider that. Pre-terminated isn't really expensive.

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