diff --git a/homeassistant/components/synology_dsm/const.py b/homeassistant/components/synology_dsm/const.py
index 5bae7426769..9bd4728643a 100644
--- a/homeassistant/components/synology_dsm/const.py
+++ b/homeassistant/components/synology_dsm/const.py
@@ -353,7 +353,7 @@ INFORMATION_SENSORS: tuple[SynologyDSMSensorEntityDescription, ...] = (
     SynologyDSMSensorEntityDescription(
         api_key=SynoDSMInformation.API_KEY,
         key="temperature",
-        name="temperature",
+        name="Temperature",
         native_unit_of_measurement=TEMP_CELSIUS,
         device_class=DEVICE_CLASS_TEMPERATURE,
         state_class=STATE_CLASS_MEASUREMENT,
@@ -362,7 +362,7 @@ INFORMATION_SENSORS: tuple[SynologyDSMSensorEntityDescription, ...] = (
     SynologyDSMSensorEntityDescription(
         api_key=SynoDSMInformation.API_KEY,
         key="uptime",
-        name="last boot",
+        name="Last boot",
         device_class=DEVICE_CLASS_TIMESTAMP,
         entity_registry_enabled_default=False,
         entity_category=ENTITY_CATEGORY_DIAGNOSTIC,
diff --git a/homeassistant/components/synology_dsm/sensor.py b/homeassistant/components/synology_dsm/sensor.py
index 1aa7e35d992..305e6dda4e7 100644
--- a/homeassistant/components/synology_dsm/sensor.py
+++ b/homeassistant/components/synology_dsm/sensor.py
@@ -1,7 +1,7 @@
 """Support for Synology DSM sensors."""
 from __future__ import annotations
 
-from datetime import timedelta
+from datetime import datetime, timedelta
 from typing import Any
 
 from homeassistant.components.sensor import SensorEntity
@@ -164,7 +164,7 @@ class SynoDSMInfoSensor(SynoDSMSensor):
         """Initialize the Synology SynoDSMInfoSensor entity."""
         super().__init__(api, coordinator, description)
         self._previous_uptime: str | None = None
-        self._last_boot: str | None = None
+        self._last_boot: datetime | None = None
 
     @property
     def native_value(self) -> Any | None:
@@ -176,8 +176,7 @@ class SynoDSMInfoSensor(SynoDSMSensor):
         if self.entity_description.key == "uptime":
             # reboot happened or entity creation
             if self._previous_uptime is None or self._previous_uptime > attr:
-                last_boot = utcnow() - timedelta(seconds=attr)
-                self._last_boot = last_boot.replace(microsecond=0).isoformat()
+                self._last_boot = utcnow() - timedelta(seconds=attr)
 
             self._previous_uptime = attr
             return self._last_boot