how to get the MAC address of client?

I have a client server program using UPD created in MFC. In the server there are two listboxes. The first one displays the ip addresses of the connected clients.
I want the second listbox to display the MAC address when i click the ip address from the listbox.

So how can I get the MAC address of the client by clicking the ip address in the first listbox?

so i used this code to get the MAC address:

Code:

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IP_ADAPTER_INFO AdapterInfo[16];                        // Allocate information for up to 16 NICs
        DWORD dwBufLen = sizeof(AdapterInfo);                // Save the memory size of buffer

        DWORD dwStatus = GetAdaptersInfo(                        // Call GetAdapterInfo
                AdapterInfo,                                                        // [out] buffer to receive data
                &dwBufLen);                                                                // [in] size of receive data buffer
        assert(dwStatus == ERROR_SUCCESS);                        // Verify return value is valid, no buffer overflow

        PIP_ADAPTER_INFO pAdapterInfo = AdapterInfo;// Contains pointer to current adapter info
        do {
                PrintMACaddress(pAdapterInfo->Address);        // Print MAC address
                pAdapterInfo = pAdapterInfo->Next;                // Progress through linked list
        }
        while(pAdapterInfo);                                                // Terminate if last adapter
}

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the code above just provides the currents computer mac address so it doesn't matter which ip address i click in the listbox because it only displays the same mac address
can someone please provide some code to do this