使用Boost.Beast的C++ WebSocket客户端遇Connection refused问题

我编写了如下Python WebSocket服务端代码（Server.py），通过localhost:8765发送随机数，且已用另一个Python客户端脚本（Client.py）验证该服务端可正常工作：

# Server.py
import asyncio
import websockets
import random

async def random_number(websocket, path):
    while True:
        number = random.randint(1, 100)
        await websocket.send(str(number))
        await asyncio.sleep(1)

start_server = websockets.serve(random_number, "localhost", 8765)

asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever()

# Client.py
import asyncio
import websockets

async def websocket_client():
    uri = "ws://localhost:8765"
    async with websockets.connect(uri) as websocket:
        while True:
            message = await websocket.recv()
            print(f"Received: {message}")

asyncio.get_event_loop().run_until_complete(websocket_client())

现在我希望用C实现与Client.py完全相同的功能，于是编写了基于Boost.Beast库的C WebSocket客户端代码：

#include <boost/beast/core.hpp>
#include <boost/beast/websocket.hpp>
#include <boost/asio/connect.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <cstdlib>
#include <iostream>
#include <string>

namespace beast = boost::beast;
namespace http = beast::http;
namespace websocket = beast::websocket;
namespace net = boost::asio;
using tcp = boost::asio::ip::tcp;

int main(int argc, char* argv[]) {
    try {
        const std::string host = "localhost";
        const std::string port = "8765";
        const std::string target = "/";

        net::io_context ioc;
        tcp::resolver resolver{ioc};
        websocket::stream<tcp::socket> ws{ioc};

        auto const results = resolver.resolve(host, port);
        net::connect(ws.next_layer(), results.begin(), results.end());

        ws.handshake(host + ':' + port, target);

        for (;;) {
            beast::flat_buffer buffer;
            ws.read(buffer);
            std::string message = beast::buffers_to_string(buffer.data());
            std::cout << "Received: " << message << std::endl;
        }
    }
    catch (std::exception const& e) {
        std::cerr << "Error: " << e.what() << std::endl;
        return EXIT_FAILURE;
    }
}

但运行该C++客户端时出现错误：Error: connect: Connection refused，请问这是什么原因？

内容的提问来源于stack exchange，提问作者IceCode