title: gRPC stopped working with APO on Windows 11
body: <p>I have a Windows application (APP) and Audio Processing Object (APO) loaded by AudioDG.exe that communicate via gRPC:</p>
  <ol>
  <li>APP part that is written in C# creates server via Grpc.Core.</li>
  <li>APO part creates client via grpc++.</li>
  <li>Server is on 127.0.0.1:20000 (I can see it's up and listening with <code>netstat -ano</code>).</li>
  <li>I can confirm that APO is loaded into audio device graph by inspecting it with process explorer.</li>
  </ol>
  <p>Everything worked like a charm on Windows 8 and 10, but on 11 it cannot communicate at all - I get either <code>Error Code 14, Unavailable, failed to connect to all addresses</code> or <code>4, Deadline Exceeded</code>.</p>
  <p>After enabling debug traces, I now see &quot;socket is null&quot; description for &quot;connect failed&quot; error:
  <code>I0207 16:20:59.916447 0 ..\..\..\src\core\ext\filters\client_channel\subchannel.cc:950: subchannel 000001D8B9B01E20 {address=ipv4:127.0.0.1:10000, args=grpc.client_channel_factory=0x1d8bb660460, grpc.default_authority=127.0.0.1:10000, grpc.internal.subchannel_pool=0x1d8b8c291b0, grpc.primary_user_agent=grpc-csharp/2.43.0 (.NET Framework 4.8.4470.0; CLR 4.0.30319.42000; net45; x64), grpc.resource_quota=0x1d8b8c28d90, grpc.server_uri=dns:///127.0.0.1:10000}: connect failed: {&quot;created&quot;:&quot;@1644240059.916000000&quot;,&quot;description&quot;:&quot;socket is null&quot;,&quot;file&quot;:&quot;..\..\..\src\core\lib\iomgr\tcp_client_windows.cc&quot;,&quot;file_line&quot;:112}</code></p>
  <p>What I've tried so far:</p>
  <ol>
  <li>Updating both parts to the latest grpc versions.</li>
  <li>Using &quot;no proxy&quot;, &quot;Http2UnencryptedSupport&quot; and other env variables.</li>
  <li>Using &quot;localhost&quot; or &quot;0.0.0.0&quot; instead of &quot;127.0.0.1&quot;.</li>
  <li>Updating connection to use self signed SSL certificates (root CA, server cert + key, client cert + key).</li>
  <li>Adding inbound / outbound rules for my port, and then disabling firewall completely.</li>
  <li>Creating server on APO side and trying to connect with the client in APP.</li>
  </ol>
  <p>Everything works (both insecure and SSL creds) if I create both client and server in C# part, but as soon as it's APP-APO communication it feels blocked or sandboxed.</p>
  <p>What has been changed in Windows 11 that can &quot;block&quot; gRPC?</p>
  <p>Thanks in advance!</p>