Host network port Failure Analysis and locating

1 fault symptom
My colleagues in the Department had remote access through the network in the office. They had been normal before and suddenly could not be remotely accessed yesterday.
2 positioning process
They once assigned a fixed IP address to the NIC, and the default IP address of the gateway cannot be pinged. The two NICs on the server have been tried, and the phenomenon is the same.
Are two NICs broken? The probability should be very low.
When I arrived at the lab, I found that the fixed IP address configured by the technical support staff on the server was still there. By default, the gateway cannot be pinged, and the result is: Destination host unreachable. Generally, this display means that a packet routing problem occurs. You need to check the route table and the MAC table. I used route print to check the route table, but no exception was found. I used arp-a to view the MAC table, and the gateway's MAC address is also in.
Is there a problem with the NIC Driver? The NIC driver has not changed.
The server has an Ethereal Installation File. Therefore, install Ethereal and capture packets to check whether the PING request has been sent to the NIC. The result shows that some broadcast packets, such as DHCP and ARP packets, can be captured by other computers on the LAN, which indicates that the NIC can receive normally. However, if the PING request fails, the TCP/IP module does not send the PING request to the NIC through the NDIS interface.
Change the IP address of the network adapter to automatically get the IP address. Packet capture, although there are DHCP packets, but the source MAC address is not local. In other words, Etheral cannot catch the DHCP request, indicating that the DHCP request is not sent to the NIC. Check whether the DHCP client Service has been started. Disabled, and then enabled. The phenomenon does not change. It is likely that the DHCP request is not sent to the NIC by the TCP/IP module through the NDIS interface.