Member Avatar for Yogesh1983

I'm having problems connecting my computer with my laptop to share my cable modem inernet connection;
for some reason the connection between the laptop and pc keeps saying "a nerwork cable is unplugged", though it is connected and yes, the cables i used are correct en working. How do i know that? I've connected another laptop to this pc before, using the same ethernetcard and cable and it worked!!! I did get the message "Low connectivity" back then, but I solved it by turning off the "Obtain automatic ip adress automayically" and specify a different adress for the 2 computers.
But now, I don't even get that, I only get "a nerwork cable is unplugged"!!!! Why is that??
Who can help me?

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described a classic split between “works to the modem” and “no link when laptop is plugged into the PC.” Threads from , and already covered cable type and router vs. switch—the next step is a short, focused diagnostic flow that separates physical-layer failures (cable/port/NIC) from OS/driver or sharing-configuration problems.

Check the physical layer and adapter state first: confirm link/activity LEDs on both NICs when the cable is plugged in; note which side (PC or laptop) shows no LED. Inspect Device Manager for errors, disable any NIC power-saving option, uninstall/reinstall the NIC driver, and run the Windows network troubleshooter. Capture the adapter state from a command prompt and try a quick reset/ping sequence:

ipconfig /all
netsh int ip reset
ipconfig /release
ipconfig /renew
ping 192.168.0.1

If the link LED stays off while the other end shows link, the problem is almost always physical (bad jack, broken pair, or a failed NIC). A simple cable-continuity or pinout test with a handheld tester (or multimeter) will confirm wiring/pair integrity; a basic continuity tester is far quicker than guessing cables. (platinumtools.com)

When PC-to-PC links fail but both NICs work to the modem, check negotiation and cable type: many modern NICs implement Auto-MDIX so crossover vs straight is usually handled automatically, but Auto-MDIX requires auto-negotiation on at least one side. If a NIC was forced to a fixed speed/duplex (or the cable only has two pairs), the link can fail—forcing both ends to the same safe setting (for older gear, 100 Mbps / full duplex) is a useful test. (cisco.com)

If the physical link is green, then reconsider sharing setup: Windows ICS will create a private subnet and act as gateway for the other machine (Windows docs cover the behavior and limitations). If buying hardware is an option, a small NAT router or even an inexpensive switch + a host doing NAT/ICS (with firewall off while testing) will simplify things once the link problem is fixed. (learn.microsoft.com)

Summary checklist: confirm LEDs, swap ports/cables, try a known-good USB-Ethernet on the laptop, test continuity with a cable tester, force matching speed/duplex for a short trial, then re-check ICS/NAT once the link is stable.

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Member Avatar for alc6379

Are you using a crossover cable, or a straight through? Some systems can't use a straight cable hooked to another PC.

Member Avatar for Yogesh1983

I already used the cable, that I'm using now, in the past to connect with another laptop and it worked(i could transfer files from one to another pc). I even switched the UTP cable that i used for the internet with the one i used for connection between pc's(that cable also worked when I helped a friend to connect his laptop to his pc).
This al was just a month ago; what are the chances both cables malfunctioning in such a short period?? I'd say none, don't you think so too? ;)

I think I'm using a crossover cable, but I'm not sure. On both connectors, I can see "X' over".I think that means crossover, right? thanks

Member Avatar for kc0arf

Hello,

For $30 to $40, you can get a small ethernet hub / switch, and remove all confusion involving crossover cables vs. normal ones. Save yourself the grief, and get the proper hardware.

Christian

Member Avatar for DMR

"X over" indicates a crossover cable, yes.

Do you get the "cable unplugged" error when you plug the laptop directly into the cable modem, or when the laptop is plugged into any other network device aside from your desktop machine?

Hello,

For $30 to $40, you can get a small ethernet hub / switch...

A hub or switch won't usually do the trick on a Cable or DSL Internet connection, as the ISPs only allow/provide 1 IP address with normal Internet access accounts. You can physically connect more than one computer to the hub/switch, but only the first computer to log on to the Internet will be authorized, receive an IP, and be able to surf; the second computer will be denied access.

A broadband router provides the functionality needed, but they do cost more than a hub or simple switch (a good router runs around $60 USD).

Member Avatar for Yogesh1983

Yes, I know all that. :) My ISP is from my university and according to a friend a hub won't do the trick; a router would. But the problem is that I'm a very poor engineering student, and I can't afford an expensive router(in Belgium the min. price is about 70 euro for a router!!!!!!!). But i do have the 3 ethernetcards; so you see my dilemma.

And I only get the unplugged error when there is a connection between laptop and pc. I can surf on the internet with both computers(over de cable modem connection).

Member Avatar for DMR

Let me ask a possibly stupid question:
Regardless of the fact that you're getting the message about the unplugged cable, do the two computers appear to be communicating at all? Can you ping each machine from the other? If the laptop is set for DHCP and the desktop is configured to provide an IP to the laptop, does it?

Member Avatar for Yogesh1983

no connectivity at all!! when i try the ipconfig command in cmd window i get "media disconected", as I expected.

Member Avatar for DMR

Look under the Advanced tab in the hardware properties of each computer's NIC and make sure that the Link, Duplex, etc. settings are in agreement with the way the NICs should be communicating/negotiating. If the NICs are currently set to auto detect their speed and duplex modes, hard-set those options to the correct settings (100Mbps/Full Duplex, 1Gbps/Half Duplex, etc.)

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