Use the same Wi-Fi
Connect your iPhone to the same trusted network as the air conditioner. Guest networks often isolate devices from each other.
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Keep troubleshooting local, too.
Most connection issues come down to network access, Wi-Fi isolation or a saved local endpoint. Start with these checks.
Allow Local Network access
Open iOS Settings, find OpenAirco and enable Local Network. Reopen the app afterwards.
Search again
Keep the app open during discovery. If a saved unit is unreachable, use reconnect before removing it.
Restart the local path
Restart the air conditioner's Wi-Fi interface and your iPhone connection, then search once more.