diff --git a/backend/app/api/routes/iot_gateway.py b/backend/app/api/routes/iot_gateway.py
index fc63e8ab..07816ab1 100644
--- a/backend/app/api/routes/iot_gateway.py
+++ b/backend/app/api/routes/iot_gateway.py
@@ -87,8 +87,26 @@ async def gateway_proxy(client_id: str, path: str, request: Request) -> Response
         if overlay_resp is not None:
             return overlay_resp
 
+    # Wording matters here. The old text said "make sure your sketch connected
+    # to WiFi", which reads as an accusation to the one sketch that most often
+    # lands on this branch: a captive-portal / provisioning sketch that called
+    # WiFi.softAP() and deliberately did NOT join a network. Such a board is
+    # the access point, so it never gets a DHCP lease, never reaches 'got_ip',
+    # and never registers the bridge this proxy looks up — there is nothing to
+    # reach and nothing the user did wrong. Name that case first.
     return Response(
-        content='{"error":"No WiFi-enabled board found for this client. Make sure your sketch connected to WiFi and started a server on port 80."}',
+        content=json.dumps({
+            'error': 'no_reachable_board',
+            'message': (
+                'Nothing is registered for this client, so there is no server '
+                'to reach. If your sketch calls WiFi.softAP(), that is why: '
+                'the simulator can reach a board that JOINED a network, not a '
+                'board that created one. Join a simulated network instead '
+                '(WiFi.begin("Velxio-GUEST") — open, no password) and start '
+                'your server on port 80. If the sketch does join a network, '
+                'wait for it to print its IP before opening the gateway.'
+            ),
+        }),
         status_code=404,
         media_type='application/json',
     )
diff --git a/frontend/src/components/simulator/SerialMonitor.tsx b/frontend/src/components/simulator/SerialMonitor.tsx
index 014a3d49..01490bb3 100644
--- a/frontend/src/components/simulator/SerialMonitor.tsx
+++ b/frontend/src/components/simulator/SerialMonitor.tsx
@@ -293,7 +293,20 @@ export const SerialMonitor: React.FC = () => {
               // the emulated network. The trailing dot-check keeps a longer
               // address like 192.168.4.15.99 from half-matching.
               const ipRegex = /(?:http:\/\/)?(?:192\.168\.4|10\.13\.37)\.(\d{1,3})(?!\d|\.\d)(\/[^\s]*)?/g;
-              const matches = [...text.matchAll(ipRegex)];
+              // ...but ONLY once the board actually joined a network. A sketch
+              // that calls WiFi.softAP() becomes the access point instead of a
+              // client, and the ESP32's SoftAP default address is 192.168.4.1
+              // — the very subnet above. The address alone cannot tell the two
+              // apart, so a captive-portal sketch used to get a gateway link
+              // that could never resolve: the bridge the proxy looks up is
+              // registered on 'got_ip', which only a STATION ever reaches, so
+              // the click landed on a 404 telling the user to connect to WiFi
+              // when the sketch had deliberately chosen not to. Gate on the
+              // status every family reports: QEMU (wifi_status_parser),
+              // the in-browser JS engines, and the Pico W's cyw43 peripheral
+              // all emit 'got_ip'. Without it the IP stays plain text.
+              const reachable = activeBoard.wifiStatus?.status === 'got_ip';
+              const matches = reachable ? [...text.matchAll(ipRegex)] : [];
 
               if (matches.length > 0) {
                 const parts: (string | React.ReactNode)[] = [];
diff --git a/test/backend/unit/test_esp32_wifi_webserver.py b/test/backend/unit/test_esp32_wifi_webserver.py
index e5e01da6..b35de0cb 100644
--- a/test/backend/unit/test_esp32_wifi_webserver.py
+++ b/test/backend/unit/test_esp32_wifi_webserver.py
@@ -246,6 +246,26 @@ class TestHttpServerDetection(unittest.TestCase):
 class TestIoTGatewayUrl(unittest.TestCase):
     """Test IoT Gateway URL construction for the WebServer sketch."""
 
+    def test_unreachable_message_names_softap_instead_of_blaming_the_sketch(self):
+        """The 404 a captive-portal sketch hits must explain WHY, not accuse.
+
+        A sketch that calls WiFi.softAP() is the access point: it never gets a
+        DHCP lease, never reaches 'got_ip', and so never registers the bridge
+        the proxy looks up. The old copy said "make sure your sketch connected
+        to WiFi", which is exactly what such a sketch deliberately did not do.
+        """
+        import re
+        from pathlib import Path
+
+        route = Path(__file__).resolve().parents[3] / 'backend/app/api/routes/iot_gateway.py'
+        src = route.read_text(encoding='utf-8')
+        # The accusatory sentence must be gone...
+        self.assertNotIn('Make sure your sketch connected to WiFi and started', src)
+        # ...and the replacement must name softAP and point at a real network.
+        tail = src[src.index('no_reachable_board'):]
+        self.assertIn('WiFi.softAP()', tail)
+        self.assertIn('Velxio-GUEST', tail)
+
     def test_root_gateway_url(self):
         client_id = 'board-1'
         url = f'http://localhost:8001/api/gateway/{client_id}/'