Solve the problem of network network card "memory effect" causing disconnection

Recently, schools have decided to revamp the office layout so that two computers already networked in the office must be readjusted. Both computers are able to access the Internet properly before adjusting. In order to ensure that two computers can share the only one cable socket in the office, we put the two computers together. After the correct physical connection and set the parameters, open two computers respectively, found that a computer can be normal access to the Internet, B computer is not connected to the Internet
On Check the LEDs on the ports on the switch end and the B computer to see that the LEDs are not lit.

The author carefully analyzed the above phenomenon, that a computer since the Internet, it indicates that the office of the network cable sockets and the switch itself does not have hardware problems, so the author will focus on the computer and the computer to the switch between the network connection above. The author first found the wire detector, the network line between the computer and the switch was tested, and the test result ruled out the reason of network impassability.

Is there a problem with the interface between the two ends of the network line connection? To verify that the network connection port on the switch is valid, the author first put the switch end nail computer corresponding to the network cable connectors in the second computer interface, the results found that a computer can be normal access to the network, the switch port is no problem, and then check the computer side of the Wire crystal Head, did not find contact with the phenomenon of bad. The author of the computer to kill virus, can be anti-virus after the internet is still not, it is obvious that the fault is unrelated to the virus.

Under the helpless, suddenly think of the "owner" of Computer B because busy to deal with the material at hand, before I plug the network cable into the network card, b computer has been started and run, and a computer was closed. The author immediately in the second computer this side of the same operation: first the network cable on Computer B unplug, and then shut down the computer, and then shut down the computer, and then reinsert the network cable into the computer network card, and restart the computer. After successful startup, open the browser, find the Internet back to normal!

To summarize the causes of the above failures, I think it is very likely that in the boot state, the network card and switch connection, the parameter information of the switch is triggered by the internal circuit, resulting in the work of the "unstable", the network card to this "unstable" produced a "memory effect", resulting in the normal network connection. In general, the use of well-known, good quality network card or switch, it is difficult to encounter the above strange phenomenon.