Amazon Q Sign-in Fails with ETIMEDOUT on Ubuntu

Hello, I am unable to sign in to Amazon Q in VS Code on Ubuntu. I am consistently getting an ETIMEDOUT error in the logs when the extension tries to connect to oidc.us-east-1.amazonaws.com.

We have already performed extensive troubleshooting, including:

Confirmed that network access from the terminal works perfectly (curl https://google.com is successful).

Found and removed an invalid system-wide proxy setting.

Ensured all proxy environment variables (https-proxy, HTTP_PROXY, etc.) are unset in the shell.

Reset the GNOME gsettings proxy configuration to mode 'none'.

Confirmed VS Code is not a Snap package.

Performed a complete purge and reinstall of VS Code, which included manually deleting ~/.config/Code and ~/.vscode.

The issue still occurs in a fresh installation launched from a clean terminal.

logs:

2025-09-12 11:03:56.043 [warning] telemetry: invalid Metric: "amazonq_mcpConfig" emitted without the `result` property, which is always required. Consider using `.run()` instead of `.emit()`, which will set these properties automatically. See https://github.com/aws/aws-toolkit-vscode/blob/master/docs/telemetry.md#guidelines
2025-09-12 11:03:56.043 [info] [Info - 11:03:56 AM] [2025-09-12T05:33:56.041Z] lserver: ProfileStatusMonitor started - checking MCP configuration every 24 hours
2025-09-12 11:04:00.970 [info] [2025-09-12T05:34:00.969Z] lserver: Amazon Q Token Service Manager: No active SSO connection is detected: no credentials provided. Resetting the client
2025-09-12 11:04:05.971 [info] [2025-09-12T05:34:05.970Z] lserver: Amazon Q Token Service Manager: No active SSO connection is detected: no credentials provided. Resetting the client
2025-09-12 11:04:10.972 [info] [2025-09-12T05:34:10.971Z] lserver: Amazon Q Token Service Manager: No active SSO connection is detected: no credentials provided. Resetting the client
2025-09-12 11:04:15.972 [info] [2025-09-12T05:34:15.971Z] lserver: Amazon Q Token Service Manager: No active SSO connection is detected: no credentials provided. Resetting the client
2025-09-12 11:04:16.609 [info] selected AWS ID sign in
2025-09-12 11:04:16.609 [info] auth: Updating connection state of 1d4aacd5-d644-4f13-a5c1-d3861ad6ab2c to authenticating
2025-09-12 11:04:16.609 [info] codewhisperer: connection changed to authenticating: 1d4aacd5-d644-4f13-a5c1-d3861ad6ab2c
2025-09-12 11:04:16.611 [info] current client registration id=undefined
expires at undefined
key = 1d4aacd5-d644-4f13-a5c1-d3861ad6ab2c
2025-09-12 11:04:17.447 [error] API response (oidc.us-east-1.amazonaws.com /client/register): { code: 'ETIMEDOUT', name: 'TimeoutError' }
2025-09-12 11:04:18.278 [error] API response (oidc.us-east-1.amazonaws.com /client/register): { code: 'ETIMEDOUT', name: 'TimeoutError' }
2025-09-12 11:04:19.333 [error] API response (oidc.us-east-1.amazonaws.com /client/register): { code: 'ETIMEDOUT', name: 'TimeoutError' }
2025-09-12 11:04:19.337 [error] ssoSetup encountered an error: Error: Failed to connect to AWS Builder ID [FailedToConnect]
-> TimeoutError: [ETIMEDOUT]
2025-09-12 11:04:19.337 [error] webviewId="aws.amazonq.AmazonCommonAuth": Error: Webview error
-> Error: Webview backend command failed: "startCodeWhispererBuilderIdSetup()"
-> Error: Failed to connect to AWS Builder ID [FailedToConnect]
-> TimeoutError: [ETIMEDOUT]
2025-09-12 11:04:20.972 [info] [2025-09-12T05:34:20.971Z] lserver: Amazon Q Token Service Manager: No active SSO connection is detected: no credentials provided. Resetting the client

Start with the Amazon Q sign-in flow named in the logs, especially startCodeWhispererBuilderIdSetup() and the request to oidc.us-east-1.amazonaws.com/client/register. Reproduce the failure from a clean VS Code installation on Ubuntu and compare it with the reported proxy and curl checks; done means the cause of the ETIMEDOUT failure is identified and sign-in succeeds or the remaining environmental limitation is documented.

Written by the indexing model from the issue text.