[SOLVED] [Solved] New Ethernet Cable not working on Desktop PC, but works on Laptop ?

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Feb 9, 2022
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Hello Everyone

I got a real tricky issue with my Desktop PC.

Recently I got a new Ethernet cable(15m) for my Desktop PC which my PC didn't recognize, here is the details of the connection:

15m cable to the Wall --> connects to a wall Ethernet inline adapter --> then another 15m cable runs to directly to the Router

Here's the issue, my PC tries to recognize it then fails, it loops at "Identifying" which it never does successfully.

All these 30m of cable connected to a laptop (I tested 2 actually) and it works without problems.

Since I thought maybe the Ethernet Port was faulty, I tested my Desktop PC again with only the old 15m Cable to the router, it works.

I verified the pin order on the new cable is the same as the old, I tested only with the new 15m cable, doesn't work on Desktop PC either but works on laptops.

I then purchased an Ethernet-to-USB Adapter and funny thing is it worked for like 15 minutes, then same issue, doesnt recognize the connection, loops on Identifying network. which in the end doesn't detect anything connected.

I was wondering if the distance is an issue (30m) but I even tested with only the new 15m cable but same problem (old 15m works).

Any ideas on what might be the issue?
 

Ralston18

Titan
Moderator
Yes the desktop port might just be squeezing the plug/connector in just some manner that creates a short.

You could try changing the plugs yourself but likely to be a matter of trial and error to replace the plugs.

Plus you need to get crimpers and the correct connectors for the wire.

FYI (and you can easily find other similar "how to" type links).

https://pinouts.ru/NetworkCables/ethernet_10_100_1000_pinout.shtml

= = = =

Also:

About Modular Connector Plugs and Jacks:
The 8P8C modular connectors for Ethernet are often called RJ45 due to their physical resemblance. The plug is an 8-position modular connector that looks like a large phone plug. There are a couple variations available. The primary variation you need to pay attention to is whether the connector is intended for braided or solid wire. For braided/stranded wires, the connector has sharp pointed contacts that actually pierce the wire. For solid wires, the connector has fingers which cut through the insulation and make contact with the wire by grasping it from both sides. The connector is the weak point in an ethernet cable, choosing the wrong one will often cause grief later. If you just walk into a computer store, it's nearly impossible to tell what type of plug it is. You may be able to determine what type it is by crimping one without a cable.
Modular connector jacks come in a variety styles intended for several different mounting options. The choice is one of requirements and preference. Jacks are designed to work only with solid ethernet cable. Most jacks come labeled with color coded wiring diagrams for either T568A, T568B or both. Make sure you end up with the correct one.

Source: https://www.ertyu.org/steven_nikkel/ethernetcables.html

= = = =

Use a magnifying glass and good lighting to examine the connectors up close. Compare all of the connectors on the working cables and the non-working cable. You might spot something. Late thought/question: what AWG is printed on the cable?

In any case, you posted "they created those for me". Meaning the local store cut the cable to length and did the terminations /installed the connectors - correct?

With nothing else seeming to work are you able to return the cable? Get a replacement or perhaps have the store crimp on new connectors Hopefully the store will have a tester as well.

Read the above links, examine the connectors, try a couple more cable swaps etc..

Then go back.
 

Ralston18

Titan
Moderator
Distance is not an issue - good quality, to specs Ethernet cable can be run for 100 meters.

Just for the record, where was the new Ethernet cable purchased? Cable brand/ specs? UTP, rounded, pure copper Cat 5e - correct?

(Not flat, copper clad aluminum or labeled Cat 7/8...)

The only thing that I can think of is that there is just some very slight physical problem with one of the new cable's plugs.

Just enough that the fit and feel to the desktop LAN port causes connectivity to be lost. Plus the Ethernet-USB Adapter working for only 15 minutes suggests that something came loose.

When connected to the desktop does the new Ethernet cable hang in some unsupported manner? Or get twisted and bent along the cable path to the desktop?

You are doing all the right tests with swaps etc..

Mark the ends of the new cable with a piece of tape. Methodically work through all of the swaps again. If there is a failure to connect, try some gently wiggling and twisting the new cable near its' plugs.
 
Reactions: fersherls22
Feb 9, 2022
5
0
10
0
Distance is not an issue - good quality, to specs Ethernet cable can be run for 100 meters.

Just for the record, where was the new Ethernet cable purchased? Cable brand/ specs? UTP, rounded, pure copper Cat 5e - correct?

(Not flat, copper clad aluminum or labeled Cat 7/8...)

The only thing that I can think of is that there is just some very slight physical problem with one of the new cable's plugs.

Just enough that the fit and feel to the desktop LAN port causes connectivity to be lost. Plus the Ethernet-USB Adapter working for only 15 minutes suggests that something came loose.

When connected to the desktop does the new Ethernet cable hang in some unsupported manner? Or get twisted and bent along the cable path to the desktop?

You are doing all the right tests with swaps etc..

Mark the ends of the new cable with a piece of tape. Methodically work through all of the swaps again. If there is a failure to connect, try some gently wiggling and twisting the new cable near its' plugs.
Thanks for the reply!

Cable is CAT5e same as the old one as you mentioned, I purchased both of them at a local store actually so they created those for me, I was wondering too that the fact that it worked 15 minutes means something physical doesnt like my new Desktop, but it behaves the same on the Ethernet to usb adapter, its a new lan "port" and with this is where it worked like 15 minutes.

Tried twisting it so see if it was doing some false contact but didnt worked, funny is I did the same bending connected to a laptop expecting to fail or be intermitent but it wasnt the case, laptops worked even when I bent the Cable on purpose.

Should I try to Change the plugs?
 

Ralston18

Titan
Moderator
Yes the desktop port might just be squeezing the plug/connector in just some manner that creates a short.

You could try changing the plugs yourself but likely to be a matter of trial and error to replace the plugs.

Plus you need to get crimpers and the correct connectors for the wire.

FYI (and you can easily find other similar "how to" type links).

https://pinouts.ru/NetworkCables/ethernet_10_100_1000_pinout.shtml

= = = =

Also:

About Modular Connector Plugs and Jacks:
The 8P8C modular connectors for Ethernet are often called RJ45 due to their physical resemblance. The plug is an 8-position modular connector that looks like a large phone plug. There are a couple variations available. The primary variation you need to pay attention to is whether the connector is intended for braided or solid wire. For braided/stranded wires, the connector has sharp pointed contacts that actually pierce the wire. For solid wires, the connector has fingers which cut through the insulation and make contact with the wire by grasping it from both sides. The connector is the weak point in an ethernet cable, choosing the wrong one will often cause grief later. If you just walk into a computer store, it's nearly impossible to tell what type of plug it is. You may be able to determine what type it is by crimping one without a cable.
Modular connector jacks come in a variety styles intended for several different mounting options. The choice is one of requirements and preference. Jacks are designed to work only with solid ethernet cable. Most jacks come labeled with color coded wiring diagrams for either T568A, T568B or both. Make sure you end up with the correct one.

Source: https://www.ertyu.org/steven_nikkel/ethernetcables.html

= = = =

Use a magnifying glass and good lighting to examine the connectors up close. Compare all of the connectors on the working cables and the non-working cable. You might spot something. Late thought/question: what AWG is printed on the cable?

In any case, you posted "they created those for me". Meaning the local store cut the cable to length and did the terminations /installed the connectors - correct?

With nothing else seeming to work are you able to return the cable? Get a replacement or perhaps have the store crimp on new connectors Hopefully the store will have a tester as well.

Read the above links, examine the connectors, try a couple more cable swaps etc..

Then go back.
 
Feb 9, 2022
5
0
10
0
Yeah they actually showed me the Tester succesfully completed a test on the new cable, most likely if I go try to return it they will test it and find nothing wrong with it.

And since cable is exactly the same as the old, Im not sure if its something on the conectors, Ill do some testing again.

The thing that I dont understand is that I tested it with the ehternet to usb adapter and failed.(well worked 15 minutes and then nothing)

Ill get a shorter cable and test with the old and this new shorter and see how it looks
 
So what test did they run the stupid one with the little leds that just tests if pin 1 is connected to pin 1 and pin 2 is connected to pin 2 etc. That is somewhat useful but it doesn't find issues where you used the wrong color pattern and got the wire pairs mixed up.

A real tester will actually show many test results that show the cable meets all kinds of standards for certification. These meters are extremely expensive but it what professional cable makers use. If this was just some random computer shop they likely just use the cheap ones.

In any case I would now suspect the in wall cabling. It it not likely the cable itself unless it could have somehow been damaged. It is almost always the wall jacks. You can look at them but you would have to be very lucky to see a problem after it had be previously working fine.
The wires inside the jack could have been damaged or one of the wires has come slighly loose where it is punched down into the back of the jack. You could try to remove the ethernet cable wires one at a time and cut off a bit and the punch them back down. You can if you are extremely careful use a small screw driver but a real punch down tool is easier. Rather than buy a punch down tool you might consider just replacing the keystone jack. They make many that do not require tools or come with a plastic thing that works as a punch down. It likely will be about the same as buy a punch down tool.
 
Reactions: fersherls22
Feb 9, 2022
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Thanks Everyone for the help in the End it was something with the Cable that was really specific that only my Desktop didnt liked, I redid the connectors and worked!
 
Feb 9, 2022
5
0
10
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What was it? I have the exact same issue please tell me the fix
It was a physical issue with the connectors not exactly sure what, but I changed those, and the cable started working just fine, it was weird because on my laptops worked just fine, but the problem was good enough so my Desktop didnt liked it and it didnt worked there, so it was just an issue with that.
 
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