diff --git a/homeassistant/components/glances/__init__.py b/homeassistant/components/glances/__init__.py
index 44460ed1928b..ebeff5aa20e0 100644
--- a/homeassistant/components/glances/__init__.py
+++ b/homeassistant/components/glances/__init__.py
@@ -26,8 +26,9 @@ from homeassistant.exceptions import (
     ConfigEntryNotReady,
     HomeAssistantError,
 )
-from homeassistant.helpers.httpx_client import get_async_client
+from homeassistant.helpers.httpx_client import create_async_httpx_client
 
+from .const import DEFAULT_TIMEOUT
 from .coordinator import GlancesConfigEntry, GlancesDataUpdateCoordinator
 
 PLATFORMS = [Platform.SENSOR]
@@ -65,7 +66,11 @@ async def async_unload_entry(hass: HomeAssistant, entry: GlancesConfigEntry) ->
 
 async def get_api(hass: HomeAssistant, entry_data: dict[str, Any]) -> Glances:
     """Return the api from glances_api."""
-    httpx_client = get_async_client(hass, verify_ssl=entry_data[CONF_VERIFY_SSL])
+    # The shared httpx client cannot be used because its 5-second timeout
+    # is too short for slow Glances hosts.
+    httpx_client = create_async_httpx_client(
+        hass, verify_ssl=entry_data[CONF_VERIFY_SSL], timeout=DEFAULT_TIMEOUT
+    )
     for version in (4, 3):
         api = Glances(
             host=entry_data[CONF_HOST],
diff --git a/homeassistant/components/glances/const.py b/homeassistant/components/glances/const.py
index 6831ccb9e3b6..63e0bcb8c0fb 100644
--- a/homeassistant/components/glances/const.py
+++ b/homeassistant/components/glances/const.py
@@ -9,5 +9,6 @@ CONF_VERSION = "version"
 DEFAULT_HOST = "localhost"
 DEFAULT_PORT = 61208
 DEFAULT_SCAN_INTERVAL = timedelta(seconds=60)
+DEFAULT_TIMEOUT = 30
 
 CPU_ICON = f"mdi:cpu-{64 if sys.maxsize > 2**32 else 32}-bit"
diff --git a/homeassistant/components/glances/coordinator.py b/homeassistant/components/glances/coordinator.py
index d95ac1310bb8..d2d5383c3f25 100644
--- a/homeassistant/components/glances/coordinator.py
+++ b/homeassistant/components/glances/coordinator.py
@@ -47,7 +47,7 @@ class GlancesDataUpdateCoordinator(DataUpdateCoordinator[dict[str, Any]]):
         except exceptions.GlancesApiAuthorizationError as err:
             raise ConfigEntryAuthFailed from err
         except exceptions.GlancesApiError as err:
-            raise UpdateFailed from err
+            raise UpdateFailed(str(err)) from err
         # Update computed values
         uptime: datetime | None = None
         up_duration: timedelta | None = None
diff --git a/tests/components/glances/test_init.py b/tests/components/glances/test_init.py
index 16d4d9d371bb..517904055d77 100644
--- a/tests/components/glances/test_init.py
+++ b/tests/components/glances/test_init.py
@@ -1,7 +1,8 @@
 """Tests for Glances integration."""
 
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch
 
+from freezegun.api import FrozenDateTimeFactory
 from glances_api.exceptions import (
     GlancesApiAuthorizationError,
     GlancesApiConnectionError,
@@ -9,13 +10,18 @@ from glances_api.exceptions import (
 )
 import pytest
 
-from homeassistant.components.glances.const import DOMAIN
+from homeassistant.components.glances.const import (
+    DEFAULT_SCAN_INTERVAL,
+    DEFAULT_TIMEOUT,
+    DOMAIN,
+)
 from homeassistant.config_entries import ConfigEntryState
+from homeassistant.const import STATE_UNAVAILABLE
 from homeassistant.core import HomeAssistant
 
 from . import MOCK_USER_INPUT
 
-from tests.common import MockConfigEntry
+from tests.common import MockConfigEntry, async_fire_time_changed
 
 
 async def test_successful_config_entry(hass: HomeAssistant) -> None:
@@ -53,6 +59,49 @@ async def test_setup_error(
     assert entry.state is entry_state
 
 
+async def test_entity_unavailable_on_update_error(
+    hass: HomeAssistant,
+    freezer: FrozenDateTimeFactory,
+    mock_api: MagicMock,
+) -> None:
+    """Test that entities become unavailable when a data update fails."""
+    entry = MockConfigEntry(domain=DOMAIN, data=MOCK_USER_INPUT)
+    entry.add_to_hass(hass)
+
+    await hass.config_entries.async_setup(entry.entry_id)
+    await hass.async_block_till_done()
+    assert entry.state is ConfigEntryState.LOADED
+    assert hass.states.get("sensor.0_0_0_0_ssl_disk_used").state != STATE_UNAVAILABLE
+
+    mock_api.return_value.get_ha_sensor_data.side_effect = GlancesApiConnectionError(
+        "Connection to http://localhost:61209/api/4/all failed"
+    )
+    freezer.tick(DEFAULT_SCAN_INTERVAL)
+    async_fire_time_changed(hass)
+    await hass.async_block_till_done()
+
+    assert hass.states.get("sensor.0_0_0_0_ssl_disk_used").state == STATE_UNAVAILABLE
+
+
+async def test_dedicated_httpx_client_uses_timeout(
+    hass: HomeAssistant,
+) -> None:
+    """The integration's dedicated httpx client uses DEFAULT_TIMEOUT."""
+    entry = MockConfigEntry(domain=DOMAIN, data=MOCK_USER_INPUT)
+    entry.add_to_hass(hass)
+
+    with patch(
+        "homeassistant.components.glances.create_async_httpx_client"
+    ) as mock_create:
+        await hass.config_entries.async_setup(entry.entry_id)
+        await hass.async_block_till_done()
+        assert entry.state is ConfigEntryState.LOADED
+
+        kwargs = mock_create.call_args.kwargs
+        assert kwargs["timeout"] == DEFAULT_TIMEOUT
+        assert kwargs["verify_ssl"] == MOCK_USER_INPUT["verify_ssl"]
+
+
 async def test_unload_entry(hass: HomeAssistant) -> None:
     """Test removing Glances."""
     entry = MockConfigEntry(domain=DOMAIN, data=MOCK_USER_INPUT)