Buffer Size Issue with Npcap in Windows 10 using pcap.h in C++

Question

I have encountered an issue while trying to set a large buffer size using Npcap in a C++ program on Windows 10. The code works correctly when using WinPcap, obtaining the desired 2GB buffer size, but fails to achieve the same result with Npcap. I am seeking guidance on resolving this issue.

Example:

#include <iostream>
#include <pcap.h>

void packet_handler(u_char *user, const struct pcap_pkthdr *pkthdr, const u_char *packet) {
    // Your packet handling logic goes here
    // This function will be called for each captured packet
    std::cout << "Packet captured!" << std::endl;
}

int main() {
    char errbuf[PCAP_ERRBUF_SIZE];

    // Change "eth0" to your network interface name
    const char *dev = "eth0";

    // Open the capture interface
    pcap_t *handle = pcap_open_live(dev, 65536, 1, 1000, errbuf);

    if (handle == nullptr) {
        std::cerr << "Couldn't open device " << dev << ": " << errbuf << std::endl;
        return 1;
    }

    // Set the buffer size
    int buffer_size = 2147483647; // 2 GB
    if (pcap_set_buffer_size(handle, buffer_size) != 0) {
        std::cerr << "Failed to set buffer size: " << pcap_geterr(handle) << std::endl;
        return 1;
    }

    // Start capturing packets
    if (pcap_loop(handle, 0, packet_handler, nullptr) < 0) {
        std::cerr << "Error during packet capture: " << pcap_geterr(handle) << std::endl;
        return 1;
    }

    // Close the capture handle
    pcap_close(handle);

    return 0;
}

My issue is that pcap_set_buffer_size didn't Get 2GB RAM while I used Npcap!

The provided code works correctly on Windows with WinPcap, achieving the desired 2GB buffer size. However, when using Npcap, the same code fails to obtain the expected buffer size from RAM.