unfortunately over the last two releases a new issue seems to have crept in. The connection via MQTT seems to reinitialize every ~360s causing the device to become unavailable in Homeassistant and delaying or preventing the sending of commands. Furthermore it spams logs within the mqtt broker and homeassistant, causing unnecessary write cycles on top of not being able to lock/unlock or see the status of the lock.
The logs within mqtt5 look like following:
mqtt5 | 1787427912: New connection from 192.0.2.129:64179 on port 1883.
mqtt5 | 1787427913: New client connected from 192.0.2.129:64179 as Nuki_XXXXXXXX (p4, c1, k300, u'nuki').
mqtt5 | 1787428269: Client Nuki_XXXXXXXX [192.0.2.129:64179] disconnected: connection closed by client.
mqtt5 | 1787428274: New connection from 192.0.2.129:64893 on port 1883.
mqtt5 | 1787428275: New client connected from 192.0.2.129:64893 as Nuki_XXXXXXXX (p4, c1, k300, u'nuki').
mqtt5 | 1787428469: Saving in-memory database to /mosquitto/data//mosquitto.db.
mqtt5 | 1787428633: Client Nuki_XXXXXXXX [192.0.2.129:64893] disconnected: connection closed by client.
mqtt5 | 1787428638: New connection from 192.0.2.129:60459 on port 1883.
mqtt5 | 1787428639: New client connected from 192.0.2.129:60459 as Nuki_XXXXXXXX (p4, c1, k300, u'nuki').
I have checked the wifi logs and at least the wifi connection has been stable for more than 48h (no reauth, no reconn). Also my mqtt broker is not having any issues with more than 10 other devices. Additionally, the disconnect is a clean disconnect from mqtt, no network fluke or kick.
We could not reproduce the problem you describe, therefore it does not seem to apply to everyone but require a specific setup.
Could you please describe a bit your system setup (esp. which MQTT broker you are using and your network topology, how the SL is connected to the WIFI & internet, do you use VLANs and is the internet access for the Smart Lock restricted)?
If you are running a beta firmware of the Smart Lock, please send me the Nuki ID of your Smart Lock in a direct message. Thank you!
Thanks for looking into this. Happy to share my setup:
MQTT broker: the official Mosquitto broker add-on (7.1.1), running locally on my Home Assistant OS instance (not a cloud/external broker).
Network: UniFi (UDM/UniFi controller + UniFi APs), managed via the UniFi and UniFi Insights integrations in Home Assistant.
Smart Lock connectivity: no Bridge involved — this is a Smart Lock Ultra with built-in WiFi, connected directly to my 2.4GHz home network and talking straight to the local Mosquitto broker via the built-in MQTT feature. WiFi power mode is set to “Automatic” (unchanged from before the update).
VLANs: no VLAN segmentation, single flat LAN
Internet access restriction for the Smart Lock: no restriction, it has normal outbound internet access
One thing I can confirm precisely: the problem started exactly at the firmware update to 5.9.4 (06.08.2026 public release, not a beta). Before that (5.8.11) the lock only went unavailable sporadically (once every day or two). right after updating, it started flapping to unavailable roughly every ~360 seconds, matching what’s described above. I’m on the public release track, not the beta program, so no beta Nuki ID to share on that front.
Let me know if there’s specific diagnostic data (MQTT broker logs, HA logbook export, etc.) that would help narrow this down further.
Same from my side. However I have in the meantime switched to a thread based setup. With thread, both the native matter “entities” AND also mqtt was working just fine. So i suspect it has to with the wifi stack.
My setup before change to thread:
MQTT broker: the official Eclipse-Mosquitto Docker Container
Network: OpenWRT APs
Smart Lock connectivity: no Bridge involved — this is a Smart Lock Ultra with built-in WiFi, connected directly to my 2.4GHz home network and talking straight to the local Mosquitto broker via the built-in MQTT feature. WiFi power mode is set to “Automatic” (unchanged from before the update). No DNS either, connected directly via IP, User and PW.
VLANs: no VLAN segmentation, single flat LAN
Internet access restriction for the Smart Lock: no restriction, it has normal outbound internet access. However restricting outbound connections was one of the things i tried, it changed nothing.
Since i switched to Thread in the meantime, this is no issue for me anymore. But i suspect Bugreports will be coming in once users upgrade to the latest nuki release. I tried different AP, different SSID, different Wifi-PW, readding mqtt connection in nuki several times. Nothing helped.