Switch was originally connected to a machine with a 10/100Mbps adaptive network interface card to work very normally, but now the server connected to the 100Mpbs network interface card has a red light and cannot communicate. Is there a problem with switch?

This situation is caused by improper configuration. The switch’s port is likely to be forced to be set to 10Mbps, and an error will only be reported if it is connected to the 100Mbps port. The solution is: under the port configuration, restore the port speed to adaptive or force it to 100Mpbs.