When choosing a speed of 100 Mbps duplex, the cable falls off, at 10 Mbps everything is fine. why?

Question

Computer networks

Hello, in the office they ran a 4-wire twisted pair cable through the cable channel and when connected to the switch there was no reaction, they sinned about breaking the cable, but when calling, everything turned out to be in order, when choosing 10Mbps duplex network mode in the setup, the cable appeared, when switching back to 100Mbps or auto-negotiation falls off again, but a 2-pair cable should give speeds up to 100Mbps, please tell me what could be the reason?

Answer 1

offhand:
the range is long,
the attenuation is somewhere, the cable is wet, the insulation is bad, there is little inter-core resistance.
the core broke and was simply pressed - increased resistance per unit length, a
bunch of kinks with a large angle and a small rounding,
maybe just a technological jamb in the cable itself
and a bunch of other possible options ...
100 Mbps fades, and 10 Mbps breaks through.
as an option, try plugging a hub / switch into the middle of the line to amplify the signal.
but it's better to check the line.

Answer 2

incorrectly crimped

Answer 3

Does not pull, according to the equipment, your cable is 100Mbps

Answer 4

And write the type of cable. It should be marked on the side. Can be a photo.
And how long is the cable.
And why not 8 lived? He's also cheap.

Answer 5

stretched 4 core twisted pair

You can not read further ...
But I will give more reasons why it might be:
- Cable - g..no. I came across such a cable live - it is crimped honestly, all the pins are correct - but ... it does not work.
- Incorrectly crimped, under-compressed, pins mixed up ...
- Long distance
- Sharp bends, creases, damage to the cable
- Dampness, bites (for some reason, mice really like to sharpen their teeth on it)
But most likely the cable is just g..no. This is a very characteristic feature - 10Mb breaks through, because there the requirements are 10 times lower.