RE: ble nus central disconnect immediately

Vidar Berg — Tue, 13 Oct 2026 13:25:31 GMT

Hello Andre,

This connection error is expected to occur occasionally, especially when other active scanners are within range (e.g., if you are scanning for LE devices in the nRF connect app on your phone), as their scan requests may overlap with your connection request PDU. The connection error is raised when the peripheral is not responding to the request. The solution should be to simply retry the connection.

Excessive clock drift on the 32K source may also lead to this error, but then I would also expect the connection to be unstable in the cases where the connection is established successfully.

Best regards,

Vidar

Edit to clarify: There are of course other reasons why a connection request might not be received by the peer. The connection request is only sent once per attempt. Noise from other Wifi,BT,etc devices operating on the same frequency is another example. It is just that in my experience, nearby active scanners are typically the most common cause if you experience this connection error.