iOS Codex cannot connect to any Windows host: CodexAppServer.CodexClientError (Error 11)

What version of the Codex App are you using (From “About Codex” dialog)?

26.623.70822 (Released June 30, 2026)

What subscription do you have?

ChatGPT Pro

What platform is your computer?

Microsoft Windows NT 10.0.19045.0 x64

What issue are you seeing?

I cannot use Codex Mobile to connect to any Windows Codex host.

The iPhone ChatGPT app successfully detects my Windows Codex hosts and displays them in the Codex page. However, opening any host always fails.

Observed behavior:

• Initially, the page shows the loading skeleton indefinitely.
• Sometimes it changes to:

"CodexAppServer.CodexClientError (Error 11)"

• Pressing "Reconnect" repeats the same behavior.

Desktop Codex itself works normally:

• Chat works.
• Tasks work.
• Projects work.

Only the mobile bridge fails.

What steps can reproduce the bug?

Feedback ID: no-active-thread-019f2b04-54f9-70a0-b3a8-b7b7b55d2991

What is the expected behavior?

Environment

Desktop:

• Codex App 26.623.70822
• Windows 11 x64
• ChatGPT Pro account

Mobile:

• iPhone
• ChatGPT iOS 1.2026.132 (26051406691)

Steps

1. Install the latest Codex desktop app.
2. Enable mobile connections.
3. Pair the iPhone ChatGPT app with the desktop.
4. Open Codex on the iPhone.
5. Select any paired Windows host.

Expected

The mobile app should display the desktop Codex tasks and conversations.

Actual

The mobile app either:

• stays on the loading skeleton forever, or
• shows:

CodexAppServer.CodexClientError (Error 11)

The issue occurs every time.

Additional information

Additional troubleshooting already performed

• Restarted both desktop and iPhone.
• Re-paired the devices multiple times.
• Removed and added the connection again.
• Tested both Wi-Fi and cellular.
• Tested from two completely different locations.
• Tested with two different Windows computers.
• Both computers show exactly the same behavior.
• Desktop Codex works correctly on both machines.
• The iPhone successfully discovers both hosts, so discovery is working.
• Only the mobile bridge fails.

Because the issue reproduces on two independent Windows hosts using the same OpenAI account, I suspect this may be related to the Codex mobile bridge or account state rather than a local machine configuration.