No, the downstream channel commonication only takes place between the devices and the dSM, that means within the same circuit.
Data transmission between dSMs and dSS runs over twisted pair in the circuit distributor. The data will not leave the apartment or the house.
One filter module per phase (dSF) removes power disturbandes and prevents outward crosstalk i.e. outside the circuits.
If the dSS is accessible via the Internet then security measures must be taken to the same extend as for any other communication via the Internet. All technical conditions/requirements are provided.