can't connect to S1255 over modbus tcp

[scruysberghs]

I'm using the Home Assistant Nibe integration. The heat pump is connected with a cable to LAN and has ip adress 192.168.0.232. The modbus tcp option is on. (the heat pump menu is in Dutch, if that is relevant?)
I can ping the ip adres from Home Assistant. nmap doesn't show port 502 as open but I gues that is expected behaviour for modbus tcp (I see the same on inverters). nmap does show port 8888 as open on the heat pump.

I use tcp://192.168.0.232:502 as Modbus URL and left modbus Unit Identifier on 0.
I get

And the logs :

File "/usr/local/lib/python3.13/asyncio/base_events.py", line 1137, in create_connection
    sock = await self._connect_sock(
           ^^^^^^^^^^^^^^^^^^^^^^^^^
        exceptions, addrinfo, laddr_infos)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/asyncio/base_events.py", line 1040, in _connect_sock
    await self.sock_connect(sock, address)
  File "/usr/local/lib/python3.13/asyncio/selector_events.py", line 641, in sock_connect
    return await fut
           ^^^^^^^^^
  File "/usr/local/lib/python3.13/asyncio/selector_events.py", line 681, in _sock_connect_cb
    raise OSError(err, f'Connect call failed {address}')
ConnectionRefusedError: [Errno 111] Connect call failed ('192.168.0.232', 502)

Any tips on what to try to debug further?

[yozik04]

I think Modbus TCP port should be open any way to connect. What is on port 8888?