It depends on the setup of your topology, but
This is wrong anyway so I don’t know. Routers and line couplers have to be x.y.0. It may work in your installation, but it may also introduce issues when you use multiple routers etc.
Are GAs connected to this dummy device? If so then ETS is updating filter tables automatically. In not, I’d probably change the company who set this mess up 
OK. Thank you for your explanation. Dummy device has no GAs.
It was OK in the past (Gira), because Gira communicated flawlessly. ETS connection was through Gira with iETS. Now, routing must be set up for ETS. I reconfigured it yesterday. It is now possible to communicate with devices but no bus/ga monitor. I guess it is due to wrong addressing.
I made a PR replacing invalid characters with “?” to mitigate this issue in the future. Happy Hacktoberfest!