Odd Network Issue with 1 PC on the network

rob_v

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Nov 23, 2009
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18,510
Hello All,
I have a very odd thing going on with one of the PCs on my wired network.

My cable modem has 4 ports. One of those PORT1 goes directly to a PC. Lets call it PC1.

When I connect PC1 with that line, it shows no network connection.
If I put a different PC on that line, lets call it PC2, it connects w/ no issues.

If I take PC1 and connect it to another port on the cable modem, it works fine.

If I put a HUB on PORT1 - then connect PC1 to the HUB, it connects fine. if I put PORT1 directly back into PC1 - no network connection.

I have tried 2 other laptops wired directly on port 1 as well (testing all of them w/ the same network cable).
I have even replaced both connectors on the cable to see if that was an issue.

Anyone have any ideas WTH could be going on?

Thanks in advance for any suggestions.

-Rob

 
Solution
I see, I'd say there's some MAC restriction in port 1 blocking PC1, but using a hub in the middle shouldn't really circumvent the protection, anyways give it a look in the modem/router to see if there's anything like that on port1.
Assuming the same behavior happened when you tried with those 2 wired laptops, sounds like that port is dying, the port output must be very low causing the signal to reach "broken" to your PC thus unable to detect the carrier signal, a hub repowers the signal which might be the reason it works with a hub in-between, signal gets strong enough allowing the PC to correctly detect the carrier signal.
 
I see, I'd say there's some MAC restriction in port 1 blocking PC1, but using a hub in the middle shouldn't really circumvent the protection, anyways give it a look in the modem/router to see if there's anything like that on port1.
 
Solution

rob_v

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Nov 23, 2009
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18,510
Well it turns out it was a cable issue. Initially I just replaced the ends (the run goes thru the wall) and still have the issue, I finally tried a new cable,a and issue went away, connected the old cable and it came back.
Odd the laptops did not have the issue. Anyways, problem solved....thanks for the help.