I guess you asked this question because I told you to close and open the socket when updating ip. The DHCP socket does not need to be closed and opened. I told you to close and open the socket because it can cause confusion if you are communicating with a specific target.
For example, if the W5500 was communicating with the server as a TCP client, there may be a problem when transferring data to the server after your IP is changed. But this is not essential.