ipaddress.AddressValueError: Expected 4 octets in 'None'
Traceback (most recent call last):
  File "/usr/local/etc/rc.syshook.d/start/99-checkmk_agent", line 325, in do_checks
    _lines += getattr(self,_check)()
              ^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/etc/rc.syshook.d/start/99-checkmk_agent", line 948, in checklocal_openvpn
    _max_clients = ipaddress.IPv4Network(_server.get("tunnel_network")).num_addresses -2
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/ipaddress.py", line 1539, in __init__
    self.network_address = IPv4Address(addr)
                           ^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/ipaddress.py", line 1319, in __init__
    self._ip = self._ip_int_from_string(addr_str)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/ipaddress.py", line 1206, in _ip_int_from_string
    raise AddressValueError("Expected 4 octets in %r" % ip_str)