diff --git a/packages/electron/main.mjs b/packages/electron/main.mjs
index df9eb0a0..e972e614 100644
--- a/packages/electron/main.mjs
+++ b/packages/electron/main.mjs
@@ -37,6 +37,7 @@ import { createRelayDevTunnelBridge } from './relay-dev-tunnel.mjs';
 import { attachRendererRecovery } from './renderer-recovery.mjs';
 import { mintOutsideFileGrant } from '@openchamber/web/server/lib/fs/routes.js';
 import { fetchUpdateNotes } from '@openchamber/web/server/lib/changelog/update-notes.js';
+import { applyConnectAttemptTimeout } from '@openchamber/web/server/lib/network-defaults.js';
 
 const execFileAsync = promisify(execFile);
 
@@ -104,6 +105,11 @@ if (shouldIgnoreLoopbackConnectionLimit({
 })) {
   app.commandLine.appendSwitch('ignore-connections-limit', '127.0.0.1,localhost');
 }
+// This process runs quota/provider fetches under Node/undici, whose happy-eyeballs
+// default aborts each connect attempt after 250ms — distant provider endpoints
+// routinely need longer handshakes, surfacing as "fetch failed" (#3399). No-op on
+// runtimes without the setter.
+applyConnectAttemptTimeout();
 
 protocol.registerSchemesAsPrivileged([
   {
diff --git a/packages/web/bin/cli.js b/packages/web/bin/cli.js
index dd56e0ad..cdf1f201 100755
--- a/packages/web/bin/cli.js
+++ b/packages/web/bin/cli.js
@@ -72,6 +72,13 @@ import {
   printJson,
   logStatus,
 } from './cli-output.js';
+import { applyConnectAttemptTimeout } from '../server/lib/network-defaults.js';
+
+// The CLI process performs provider fetches (quota/usage, update notes) under
+// Node/undici, whose happy-eyeballs default aborts each connect attempt after
+// 250ms — distant provider endpoints routinely need longer handshakes, surfacing
+// as "fetch failed" (#3399). No-op on runtimes without the setter.
+applyConnectAttemptTimeout();
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
diff --git a/packages/web/server/lib/network-defaults.js b/packages/web/server/lib/network-defaults.js
new file mode 100644
index 00000000..32b0f82d
--- /dev/null
+++ b/packages/web/server/lib/network-defaults.js
@@ -0,0 +1,23 @@
+import net from 'node:net';
+
+// Node caps each happy-eyeballs connect attempt at 250ms by default
+// (autoSelectFamilyAttemptTimeout). TCP handshakes to provider endpoints that are
+// geographically distant routinely take 300-1500ms, so fetch() from a Node process
+// aborts every attempt (ETIMEDOUT) and surfaces "fetch failed" even though the host
+// is reachable — e.g. the z.ai quota endpoint from an IPv4-only egress (#3399).
+//
+// Every Node process entrypoint that performs provider fetches raises the
+// per-attempt cap. Family autoselection itself stays enabled, so the IPv6→IPv4
+// fallback and ::1/localhost servers keep working; disabling it instead breaks
+// local MCP servers. Runtimes without the setter (Bun's fetch path, older Node)
+// are a no-op.
+export const CONNECT_ATTEMPT_TIMEOUT_MS = 5_000;
+
+export const applyConnectAttemptTimeout = (netModule = net) => {
+  try {
+    netModule.setDefaultAutoSelectFamilyAttemptTimeout(CONNECT_ATTEMPT_TIMEOUT_MS);
+    return true;
+  } catch {
+    return false;
+  }
+};
diff --git a/packages/web/server/lib/network-defaults.test.js b/packages/web/server/lib/network-defaults.test.js
new file mode 100644
index 00000000..31ee963b
--- /dev/null
+++ b/packages/web/server/lib/network-defaults.test.js
@@ -0,0 +1,36 @@
+import { describe, expect, it, vi } from 'vitest';
+import net from 'node:net';
+
+import { applyConnectAttemptTimeout, CONNECT_ATTEMPT_TIMEOUT_MS } from './network-defaults.js';
+
+describe('applyConnectAttemptTimeout', () => {
+  it('raises the per-attempt connect timeout on runtimes that expose the setter', () => {
+    const previous = net.getDefaultAutoSelectFamilyAttemptTimeout();
+    try {
+      expect(applyConnectAttemptTimeout()).toBe(true);
+      expect(net.getDefaultAutoSelectFamilyAttemptTimeout()).toBe(CONNECT_ATTEMPT_TIMEOUT_MS);
+    } finally {
+      net.setDefaultAutoSelectFamilyAttemptTimeout(previous);
+    }
+  });
+
+  it('is a no-op on runtimes without the setter', () => {
+    expect(applyConnectAttemptTimeout({})).toBe(false);
+  });
+
+  it('survives a throwing setter', () => {
+    const setDefaultAutoSelectFamilyAttemptTimeout = vi.fn(() => {
+      throw new Error('not supported');
+    });
+    expect(applyConnectAttemptTimeout({ setDefaultAutoSelectFamilyAttemptTimeout })).toBe(false);
+  });
+
+  it('leaves family autoselection itself untouched', () => {
+    const setDefaultAutoSelectFamily = vi.fn();
+    const setDefaultAutoSelectFamilyAttemptTimeout = vi.fn();
+    applyConnectAttemptTimeout({ setDefaultAutoSelectFamily, setDefaultAutoSelectFamilyAttemptTimeout });
+    expect(setDefaultAutoSelectFamilyAttemptTimeout).toHaveBeenCalledTimes(1);
+    expect(setDefaultAutoSelectFamilyAttemptTimeout).toHaveBeenCalledWith(CONNECT_ATTEMPT_TIMEOUT_MS);
+    expect(setDefaultAutoSelectFamily).not.toHaveBeenCalled();
+  });
+});