CRC (Cyclic Redundancy Check) errors are often indicative of physical layer issues. The most common cause for such errors is a faulty cable or an improper cable type for the connection in use. Checking and, if necessary, replacing the network cable should be the first step as it's often the easiest and least expensive step to resolve these types of errors. Reconfiguring the switch port would not directly address the potential physical layer issues causing CRC errors. Upgrading the server's NIC may unnecessarily complicate troubleshooting and would not be the first step without evidence that the NIC is at fault. It is unlikely an issue with duplex mismatch would suddenly arise with a new server connection unless misconfiguration occurred during setup.