Tuya device will not connect

Err 901 / 914 with an open port means another controller owns the socket; what not to do; key, version and IP checks.

• Err 901 Unable to Connect (protocol 3.1–3.3) or Err 914 Check device key or version (3.4–3.5)
• and a plain TCP connection to port 6668 on the device succeeds

That combination is almost always another controller holding the socket: Home Assistant (LocalTuya, tuya-local, the Tuya integration in local mode), Homebridge, Node-RED, tuya-mqtt, another DSC-HUB, another tinytuya.

• Do not rotate the local key or re-pair the device to fix it. That changes the key and wipes the device's schedules, and does not clear a conflict.

1. Disable the device in every other platform (in Home Assistant: Disable device, not Remove). Stopping the automations is not enough; the integration keeps the socket open.
2. Press Probe again on the Tuya / SmartLife card (Settings › Devices › Zigbee). It should answer immediately.

• Wrong IP (DHCP moved it): reserve the address on the router and update the seat.
• The device is offline or on a different VLAN.

The device was re-paired in SmartLife. Fetch the new local key with the developer flow and update the seat.

The app is the one exception: it falls back to the cloud while the brain holds the socket, so it keeps working (until you block the device's internet, which is the point).

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DSC-Brain user guide · Tuya device will not connect · this page is edited on the site; the Notion original was retired after the mirror