Tunnel connection failed

Problem

Many developers run into a persistent “Tunnel connection failed” error when trying to connect an iPad or iPhone for debugging.
Even after reconnecting USB-C or Lightning and tapping “Trust This Computer” multiple times, the connection won’t establish.
The issue isn’t on the Mac — it’s the iPad not activating its tunneled connection properly.

What I discovered

The iPad’s Developer Mode networking stack can become unresponsive.
By enabling a few developer networking options and running the “Test Responsiveness” function, the system restarts the underlying network daemons and reopens the tunnel instantly.
No reboot, no re-pairing, no resets required.

Prerequisites

• iPad with Developer Mode enabled
• iPad and Mac on the same Wi-Fi network (or paired once via USB for trust)
• Xcode compatible with your iPad’s iOS version

Steps to fix

1. On your iPad, open Settings → Developer.
2. Scroll to Networking and turn on:
   • Network Link Conditioner → On
   • Network Override → On
3. Under the same Networking section, tap Responsiveness.
4. Inside that menu, tap Test Responsiveness and let the test run until it finishes.
   • This test measures network round-trip speed but also restarts the iPad’s internal networking daemons (mDNSResponder, configd, and developer_mode_agent).
   • While it’s testing, the iPad re-broadcasts its service and reopens the tunnel port (62078).
5. After the test completes, connect the iPad to your Mac (or keep it connected if it already is).
6. On the Mac, open Xcode → Window → Devices and Simulators and check Connect via Network for your iPad.
7. Wait 10–15 seconds. The iPad should appear with the small Wi-Fi icon — that means the tunneled connection is active again.
8. You can now unplug USB if you want to continue wirelessly.

Why it works

• Network Link Conditioner restarts the iPad’s network discovery services.
• Network Override ensures developer connections aren’t throttled or suspended.
• Test Responsiveness directly forces the iPad to re-advertise itself to usbmuxd and reopen the tunnel listener.
• Once the test completes, the Mac successfully establishes the tunnel handshake.

Notes

• This method works even if VPNs or custom network profiles are active.
• If the tunnel fails again later, simply repeat Steps 3–4 (run Test Responsiveness) — it instantly repairs the connection.
• There’s no need to clear trusted computers or restart anything on the Mac side.
• The key is performing the Test Responsiveness action to wake the iPad’s developer networking stack.

This fix has been 100% reliable for resolving “Tunnel connection failed” on iPadOS.
Run the Responsiveness test, and the tunnel reconnects immediately.