What happens when the internet disappears?
If a music stream stops when the internet goes down, the cause is fairly obvious. If the hallway light stops responding too, it feels much harder to justify. The two functions do not need the same level of dependence on an outside service.
A cloud service runs on a company’s servers. A local controller runs in the home. A locally controlled light may still depend on that controller or the home network, so “local” is useful information rather than a guarantee that nothing can fail.
Build a simple record for the essential functions: what operates them, what they rely on and what you can still do when that part is unavailable. Ask the installer to demonstrate those cases. Knowing that a light can still be operated is much more valuable than discovering an untested assumption during an outage.
Everything has a dependency
The internet drops out. A controller restarts. A sensor battery goes flat. A service changes. None should be an unimaginable event in a system expected to be used for years.
I separate essential everyday functions from conveniences and ask what each one relies on. Local communication can reduce some dependencies, but it does not remove every point of failure.
Agree what remains available
For each important function, document the fallback. Can the light still be operated from a physical control? Can the heating be adjusted? Does a manual action depend on the same unavailable hub?
Check these behaviours in the selected system. A button on the wall is not proof that it will work independently.
Test recovery too
How does the house behave when power returns? What resumes automatically and what waits for a deliberate action? A successful restart should not create an unexpected scene in an occupied room.
Keep a recovery note with the equipment record: where the controller is, who owns the accounts, where a backup is kept and who to contact. The person living there should be able to distinguish a temporary lost connection from something that needs support. Test recovery as part of handover, rather than leaving the first restart to become a household experiment.