Recreate aiohttp session on connectivity check

It seems to actually get a proper connectivity check run, we need a new
vanilla ClientSession() object.

supervisor/coresys.py

@@ -63,7 +63,7 @@ def __init__(self):
 
         # External objects
         self._loop: asyncio.BaseEventLoop = asyncio.get_running_loop()
-        self._websession: aiohttp.ClientSession = aiohttp.ClientSession()
+        self._websession = None
 
         # Global objects
         self._config: CoreConfig = CoreConfig()
@@ -96,10 +96,8 @@ def __init__(self):
         self._bus: Bus | None = None
         self._mounts: MountManager | None = None
 
-        # Set default header for aiohttp
-        self._websession._default_headers = MappingProxyType(
-            {aiohttp.hdrs.USER_AGENT: SERVER_SOFTWARE}
-        )
+        # Setup aiohttp session
+        self.create_websession()
 
         # Task factory attributes
         self._set_task_context: list[Callable[[Context], Context]] = []
@@ -548,6 +546,15 @@ def run_in_executor(
 
         return self.loop.run_in_executor(None, funct, *args)
 
+    def create_websession(self) -> None:
+        if self._websession:
+            self.create_task(self._websession.close())
+
+        # Create session and set default header for aiohttp
+        self._websession: aiohttp.ClientSession = aiohttp.ClientSession(
+            headers=MappingProxyType({aiohttp.hdrs.USER_AGENT: SERVER_SOFTWARE})
+        )
+
     def _create_context(self) -> Context:
         """Create a new context for a task."""
         context = copy_context()

supervisor/supervisor.py

@@ -270,6 +270,8 @@ async def check_connectivity(self):
         """Check the connection."""
         timeout = aiohttp.ClientTimeout(total=10)
         try:
+            # Need to recreate the websession to avoid stale connection checks
+            self.coresys.create_websession()
             await self.sys_websession.head(
                 "https://checkonline.home-assistant.io/online.txt", timeout=timeout
             )