diff --git a/pyintesishome/intesishome.py b/pyintesishome/intesishome.py
index 979953b..f5257d3 100644
--- a/pyintesishome/intesishome.py
+++ b/pyintesishome/intesishome.py
@@ -675,6 +675,13 @@ async def _set_value(self, device_id, uid, value) -> bool:
         controller effectively read-only, and it says so rather than
         hanging until the ack timeout.
 
+        The same fallback applies when the socket opens but the SET is
+        never acknowledged. The command server has been seen in that
+        half-alive state (TCP connects, no set_ack ever comes back) while
+        the portal kept delivering commands. Portal SETs carry absolute
+        values, so a SET that did arrive and is then repeated through the
+        portal is harmless.
+
         ``use_socket=False`` is exempt: that is a deliberate read-only
         controller rather than a broken socket, so it does not fall back.
         """
@@ -725,10 +732,19 @@ async def _set_value(self, device_id, uid, value) -> bool:
                 seq,
                 self._set_ack_timeout,
             )
-            return False
         finally:
             self._pending_set_acks.pop(seq, None)
 
+        if await self._portal_set_value(device_id, uid, value):
+            _LOGGER.warning(
+                "SET uid=%s value=%s delivered via the web portal after "
+                "the socket did not acknowledge it",
+                uid,
+                value,
+            )
+            return True
+        return False
+
     async def _portal_set_value(self, device_id, uid, value) -> bool:
         """Send a SET through the brand's web portal.
 
diff --git a/tests/test_pyintesishome.py b/tests/test_pyintesishome.py
index d93540c..b215ea9 100644
--- a/tests/test_pyintesishome.py
+++ b/tests/test_pyintesishome.py
@@ -1,6 +1,7 @@
 """Tests for pyintesishome."""
 
 import asyncio
+import json
 import re
 from datetime import datetime, timedelta, timezone
 from http.cookies import SimpleCookie
@@ -703,7 +704,10 @@ async def fake_ensure():
         return True
 
     with patch.object(cloud_controller, "_ensure_socket", fake_ensure):
-        with patch.object(cloud_controller, "_send_command", return_value=None):
+        with (
+            patch.object(cloud_controller, "_send_command", return_value=None),
+            patch.object(cloud_controller, "_portal_set_value", return_value=False),
+        ):
             cloud_controller._set_ack_timeout = 0.05
             await cloud_controller.set_power_on(MOCK_DEVICE_ID)
             await cloud_controller.set_power_off(MOCK_DEVICE_ID)
@@ -1057,6 +1061,76 @@ def _mock_working_portal(mock_aioresponse):  # noqa: F811
     )
 
 
+@pytest.mark.asyncio
+async def test_unacknowledged_set_falls_back_to_portal(
+    cloud_controller,
+    mock_aioresponse,  # noqa: F811
+):
+    """A socket that opens but never acks a SET must not strand the command.
+
+    The command server has been seen half-alive: TCP connects, the SET is
+    written, no set_ack ever comes back. The portal still delivers.
+    """
+    _mock_working_portal(mock_aioresponse)
+
+    async def fake_ensure():
+        cloud_controller._connected = True
+        return True
+
+    with (
+        patch.object(cloud_controller, "_ensure_socket", fake_ensure),
+        patch.object(cloud_controller, "_send_command", return_value=None),
+    ):
+        cloud_controller._set_ack_timeout = 0.05
+        assert await cloud_controller._set_value(MOCK_DEVICE_ID, 1, 1) is True
+
+    assert cloud_controller._portal_user_id == "4242"
+    assert not cloud_controller._pending_set_acks
+
+
+@pytest.mark.asyncio
+async def test_unacknowledged_set_fails_when_portal_also_fails(
+    cloud_controller,
+    mock_aioresponse,  # noqa: F811
+):
+    """No ack and no portal means the SET is reported failed, not raised."""
+    portal = PORTAL_URL[DEVICE_INTESISHOME]
+    mock_aioresponse.get(f"{portal}/login", body="maintenance page", repeat=True)
+
+    async def fake_ensure():
+        cloud_controller._connected = True
+        return True
+
+    with (
+        patch.object(cloud_controller, "_ensure_socket", fake_ensure),
+        patch.object(cloud_controller, "_send_command", return_value=None),
+    ):
+        cloud_controller._set_ack_timeout = 0.05
+        assert await cloud_controller._set_value(MOCK_DEVICE_ID, 1, 1) is False
+
+
+@pytest.mark.asyncio
+async def test_acknowledged_set_does_not_touch_the_portal(cloud_controller):
+    """An acked SET is done; the portal is only a fallback."""
+
+    async def fake_ensure():
+        cloud_controller._connected = True
+        return True
+
+    async def fake_send(message, wait_for_response=False):
+        seq = json.loads(message)["data"]["seqNo"]
+        cloud_controller._pending_set_acks[seq].future.set_result(True)
+
+    with (
+        patch.object(cloud_controller, "_ensure_socket", fake_ensure),
+        patch.object(cloud_controller, "_send_command", fake_send),
+        patch.object(cloud_controller, "_portal_set_value") as portal_set,
+    ):
+        assert await cloud_controller._set_value(MOCK_DEVICE_ID, 1, 1) is True
+
+    portal_set.assert_not_called()
+
+
 @pytest.mark.asyncio
 async def test_use_socket_false_does_not_use_the_portal_fallback(
     mock_aioresponse,  # noqa: F811