Auto Negotiaiton fails, related to cable?

[Skar78]

Hi,

First time poster.

I have an, at least for me, unusual issue and hope to get some professionals opinion.

My router connectes with a ethernet cable to a switch, and from there to different rooms. I just bought a TV for another room and planned to use the "Smart TV" feature to hook him up to my LAN.

However I noticed that for some unknown reason the TV could not optain an IP from DHCP and if i set a fixed one could also not be reached (ping) or reach anything.

So after wasting a lot of time checking out all kinds of DHCP/IP related issues I tested other Laptops on the cable (note: they did not include wall ports, but there is simply a cable hanging out of the wall ).

In the end i found out that actually my laptop also does not work with that specific cable. Same exact behaviour as the TV. However the Laptop of my girlfriend works.

To test the switch I connected my Laptop to the exact same port with a diferent cable, works.

Then i found out that if i manually set 10 Mbps fullduplex it works, so for some reason over this specific cable the auto negotiation fails!

Now we are talking about a rather long wallmounted cable and i just wonder if it could be a cable issue? Maybe too long or poor quality?

I dont have another switch to test (using Asus 1008B at the moment) and consider to buy either another switch and/or long cable for further testing.

Thank you for your help.

 

[Skar78]

I kind of forgot to mention that the tV of course does not allow to configure the speed manually, else i could set it to 10 Mbps full dupley and leave it be -.-

 

[Thatguy]

seems like you know your answer already.

There could be a cracked wire in one of the pairs. Typically you have more wattage running through a wire when going from say 100MB to 1000MB (although small, it exists) so it could be that minor threshold.

Circuits of POTS typically burn out faster than regular phones because of the increased wattage as well.

At the end of the day, a new cable.

 

[thiggins]

(note: they did not include wall ports, but there is simply a cable hanging out of the wall ).

Can you explain this? Who is "they"? How many pairs of wires in the cable and do you know what the category rating is or whether the wires are even twisted pairs?

 

[claykin]

Cable is not terminated correctly. Most likely one pair is backwards on one end. Get a cable continuity tester (Home Depot sells them) and it will quickly tell you what is incorrect.

Note, in wall cable is 99% of time solid core. The majority of RJ45 plugs are designed to be used with stranded only. You can find RJ45 plugs that will work with solid, but normally not at retail. I see installers make this mistake all the time. They should punch down the in wall cable to a Cat5e jack and then allow you to connect a proper patch cable of your desired length.