I’m testing an erased iPhone 11 (iOS 18.7.7) with a manually configured HTTP proxy during Setup Assistant.
The Wi‑Fi proxy settings include:
- Manual proxy server and port
- Authentication enabled
- Valid username and password
- Squid 6.14 with Basic authentication
- No TLS inspection or MITM
The credentials work correctly with command-line clients and with Safari after device setup.
However, Setup Assistant sends proxy requests without a Proxy-Authorization header. Squid responds with 407 Proxy Authentication Required, but the iPhone does not retry with the configured credentials.
In one controlled test, requests to albert.apple.com received 407 and activation failed. After authentication was disabled without changing the remaining proxy configuration, requests to albert.apple.com received 200 and activation succeeded. In another run, activation completed directly, but subsequent Setup Assistant services made 537 requests through the proxy. All received 407, no credentials were sent, and setup later stalled at the “Your Settings for Your New iPhone” screen.
Is authenticated HTTP proxy access expected to work during Setup Assistant? Is Basic authentication unsupported at this stage, or is this a known issue? Are any other proxy authentication methods officially supported before device setup is complete?