I am using the standard example from the Gurux.DLMS.Client.Example.python library.
To simplify the example, I added only the reading of the serial number of the meter. And everything works fine.
Next, I enclose the code in the endless loop, so that after each successful connection and reading of the serial number, the script does not terminate, but prompts the user to press the ENTER button to repeat the operation.
You mentioned in this chain that you had tested with 256 and 512 maxPduSize. Can you confirm that it works with 64-bytes or 128- bytes PDU size as well!