Home Assistant says it can't connect after a restart

Give both services a minute to finish restarting, then re-run the connection test in Settings. If it still won't connect, the community board is the place to ask.

We don’t have a single, confirmed cause for this one to point you at directly — what follows is what’s worth checking, not a diagnosis.

Give both services a moment

Home Assistant and the box’s own message broker both need to fully finish starting up before they’ll reconnect to each other. A restart that looks stuck often just needs another minute.
Re-run the connection test

The same “Test & connect” step from setup lives in Settings, and it re-checks the connection on demand rather than waiting for the next restart.
Confirm Home Assistant itself is reachable

Open its own interface directly. If Home Assistant hasn’t come back up on its own, that’s the thing to resolve first — the connection to your box can’t succeed before it does.

Still stuck?

If none of that clears it, ask on the community board — this is a scenario we want more real reports on, not just a script to run through.