If you are experiencing an issue where the ARP (Address Resolution Protocol) cache on your router is not releasing the IP address of a Linux or Unix server, it could be due to a number of factors.
One possible cause of this issue is a problem with the ARP cache on the router itself. The ARP cache is used to store the IP addresses and MAC addresses of devices on the network, and it can sometimes become corrupt or outdated. In this case, resetting the ARP cache on the router may help resolve the issue.
To reset the ARP cache on a router, you will need to consult the documentation for your specific router. The process for resetting the ARP cache may vary depending on the make and model of the router.
Another possible cause of this issue is a problem with the network configuration on the Linux or Unix server. If the server is configured to use a static IP address, it may be holding onto the IP address even when it is not in use. In this case, reconfiguring the server to use a dynamic IP address may help resolve the issue.
Finally, the issue could be caused by a problem with the network hardware or cables. If there is a problem with the network hardware or cables, it may prevent the router from releasing the IP address of the server. In this case, checking the network hardware and cables for any issues or failures may help resolve the issue.
In general, it is a good idea to troubleshoot the issue systematically by checking the router, server, and network hardware and cables in order to identify the root cause of the problem. Once the cause of the issue has been identified, you can take the appropriate steps to resolve it.