Adding a keypad code is very unreliable for months

Dear Nuki Support,

I am experiencing persistent issues creating keypad PINs via the API for my Nuki Smart Lock 3.0 Pro (black). The firmware version is the latest (3.10.7).

Specifically, I am using a PUT request to /smartlock/{smartlockId}/auth to create time-restricted keypad codes. The API often returns a 204 response, indicating success, but the PIN is not added to the keypad.

Here’s an example of a failing request:

{
  "name": "P:R3166,6slts",
  "allowedFromDate": "2025-03-25T19:59:00+01:00",
  "allowedUntilDate": "2025-03-25T21:30:00+01:00",
  "allowedWeekDays": 127,
  "allowedFromTime": 0,
  "allowedUntilTime": 0,
  "remoteAllowed": true,
  "smartActionsEnabled": true,
  "type": 13,
  "code": 838613
}

When this occurs, the Nuki web interface (when open) displays an error.
image

Furthermore, I observe the following message in the web.nuki.io websocket:

{"operationId":"67e1c7f3a4db9855db83bcea","smartlockId":...,"type":3,"reference":"67e1c7d5a4db9855db83bce9","state":2,"errorCode":-1,"id":1391243,"name":"SmartlockOperationEvent"}

The issue is intermittent. Some codes are added successfully, while others persistently fail. My server retries failed PIN creations every 5 minutes (see attached image for retry attempts).
image

Today, the following PINs failed to be added: 838613, 864666, 232333, 643523, 152433.
PIN 643523 had been failing since yesterday, but eventually succeeded today at 19:20.

This unreliability makes it impossible to depend on the API for managing keypad access.

Could you please investigate this issue? I am available to provide further information or testing as needed.

Thank you,

Martin