Can not get SSL working, PyMySQL works

[jesseklm]

the following outputs ('Ssl_version', 'TLSv1.3'):

    with pymysql.connect(
            host='mariadb.example.com', port=3307,
            user='select_only_user', passwd='secret',
            db='database1', ssl_ca='ca-cert.pem'
    ) as connection:
        with connection.cursor() as cursor:
            sql = "SHOW STATUS LIKE 'ssl_version%';"
            cursor.execute(sql)
            print(cursor.fetchone())

tried example_ssl.py (adjusted create_pool parameters and cafile) and it fails with:

pymysql.err.OperationalError: (2003, "Can't connect to MySQL server on 'mariadb.example.com'")

full traceback:

Traceback (most recent call last):
  File "C:\Users\Jesse\Documents\aiomysqltest\venv\lib\site-packages\aiomysql\connection.py", line 540, in _connect
    await self._request_authentication()
  File "C:\Users\Jesse\Documents\aiomysqltest\venv\lib\site-packages\aiomysql\connection.py", line 758, in _request_authentication
    self._reader, self._writer = await _open_connection(
  File "C:\Users\Jesse\Documents\aiomysqltest\venv\lib\site-packages\aiomysql\connection.py", line 88, in _open_connection
    transport, _ = await loop.create_connection(
  File "C:\Python39\lib\asyncio\base_events.py", line 1090, in create_connection
    transport, protocol = await self._create_connection_transport(
  File "C:\Python39\lib\asyncio\base_events.py", line 1120, in _create_connection_transport
    await waiter
  File "C:\Python39\lib\asyncio\proactor_events.py", line 395, in _loop_writing
    self._write_fut = self._loop._proactor.send(self._sock, data)
  File "C:\Python39\lib\asyncio\windows_events.py", line 534, in send
    self._register_with_iocp(conn)
  File "C:\Python39\lib\asyncio\windows_events.py", line 723, in _register_with_iocp
    _overlapped.CreateIoCompletionPort(obj.fileno(), self._iocp, 0, 0)
OSError: [WinError 87] Falscher Parameter

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\Jesse\Documents\aiomysqltest\test_aiomysql.py", line 43, in <module>
    asyncio.get_event_loop().run_until_complete(main())
  File "C:\Python39\lib\asyncio\base_events.py", line 647, in run_until_complete
    return future.result()
  File "C:\Users\Jesse\Documents\aiomysqltest\test_aiomysql.py", line 16, in main
    async with aiomysql.create_pool(
  File "C:\Users\Jesse\Documents\aiomysqltest\venv\lib\site-packages\aiomysql\utils.py", line 74, in __aenter__
    self._obj = await self._coro
  File "C:\Users\Jesse\Documents\aiomysqltest\venv\lib\site-packages\aiomysql\pool.py", line 29, in _create_pool
    await pool._fill_free_pool(False)
  File "C:\Users\Jesse\Documents\aiomysqltest\venv\lib\site-packages\aiomysql\pool.py", line 182, in _fill_free_pool
    conn = await connect(echo=self._echo, loop=self._loop,
  File "C:\Users\Jesse\Documents\aiomysqltest\venv\lib\site-packages\aiomysql\connection.py", line 75, in _connect
    await conn._connect()
  File "C:\Users\Jesse\Documents\aiomysqltest\venv\lib\site-packages\aiomysql\connection.py", line 558, in _connect
    raise OperationalError(2003,
pymysql.err.OperationalError: (2003, "Can't connect to MySQL server on 'mariadb.example.com'")

PyMySQL version 1.0.2
aiomysql version 0.1.1

Any ideas?