可以通过以下代码解决BindIPEndPointDelegate无法正常工作的问题:
HttpClientHandler handler = new HttpClientHandler();
handler.Proxy = new WebProxy("http://222.74.202.241:8080");
handler.UseProxy = true;
handler.ServerCertificateCustomValidationCallback = (message, cert, chain, policyErrors) => true;
handler.AllowAutoRedirect = false;
handler.PreAuthenticate = true;
handler.UseDefaultCredentials = false;
int maxRetries = 3;
int delay = 200;
int retry = 0;
handler.BindIPEndPointDelegate = (servicePoint, remoteEndPoint, retryCount) => {
    IPEndPoint selectedIPEndPoint = null;
    if (retry < maxRetries) {
        if (remoteEndPoint.AddressFamily == AddressFamily.InterNetwork) {
            IPAddress[] iplist = Dns.GetHostAddresses(servicePoint.Host);
            IPAddress ipv4 = iplist.FirstOrDefault(ip => ip.AddressFamily == AddressFamily.InterNetwork);
            if (ipv4 != null) {
                selectedIPEndPoint = new IPEndPoint(ipv4, 0);
            }
        }
        retry++;
        Thread.Sleep(delay);
    }
    return selectedIPEndPoint;
};
HttpClient client = new HttpClient(handler);
HttpResponseMessage response = await client.GetAsync(url);
在这个例子中,我们创建了一个新的HttpClientHandler,设置了Proxy、ServerCertificateCustomValidationCallback、AllowAutoRedirect、PreAuthenticate、UseDefaultCredentials属性。为了正确设置此代理的IP地址,我们使用了BindIPEndPointDelegate属性,并在其中添加了一个重试机制。此代码解决了BindIPEndPointDelegate无法正常工作的问题。