I’ll try, but it says it’s about Bluetooth and I’m using Wi-Fi.
Edit:
It doesn’t help but make it worse. Now it reconnects every 15 minutes or less. (And now only disconnects and doesn’t reconnect.)
So I’m waiting for the next update. Maybe then the disconnect problems will be fixed. The connection problem to private IPs is solved. Thanks for that.
What is the new delay to reconnect automatically if I E.G. reboot the machine where Mosquitto is running?
I had to reboot after Debian update, more than 20 minutes after the smart lock has still not reconnected to MQTT, even if there were some activity on the smart lock itself, it has been unlocked and locked a couple of time.
EDIT: it is now connected again, but not reconnecting even when state has changed is not really reliable in my opinion, I understood the smart lock should reconnect in the case of physical activity but it does not look to be the case for now or there is a bug.
EDIT2: I also observed perturbations to use the smart lock using smart phone (Android) without Bluetooth durring this time.
Smart lock state was very slow to be displayed and some (un)lock operations were not successful.
I wanted to bring to your attention that there seems to be an issue with the WiFi in the new Nuki 4.0 Pro.
A friend of mine, who has multiple Airbnb apartments, bought a 4.0 Pro and loses the WiFi connection regularly when used in combination with a Fritzbox. At the same time, the other 15 Nuki 3.0 Pros run normally.
I have the same issue at my home. I bought a Nuki 4.0 Pro with a Telekom Speedport 4 and experience the same regular issues with lost WiFi. After manually opening via key or Bluetooth connection, the WiFi works again until it breaks again.
We both run the latest stable firmware.
Once the SL has detected that the MQTT connection is broken (which can take up to 5min) it starts with 5s, 10s, 20s, … reconnect tries until it reaches the maximum interval of 1h.
That was a specific problem in your case that was not related to the MQTT retry mechanism. We’re looking into it.
We appreciate any feedback, but this is a beta tester forum. If you want to contribute, please sign up for the beta and report the problems/findings in the 4th gen beta thread.
This is not feasible because there is no single “root cause” to solve. The Smart Lock requires certain power saving mechanisms to work (otherwise the batteries would be empty within a few days). There are millions of different combinations of routers, home lan/wifi settings, internet providers out there. Our goal is to work with most of them, but we’re also realistic and know that it will never work perfectly fine with all of them. Some will always work better (= more stable and lower power consumption) than others. Debugging one single setup does not solve the problem of all others.
Ok … clear…
I confirm that in my case now it is ALWAYS reconnecting… even if it disconnects regularly with apparently no reason (or the reason is the power mechanism)…
For me now it is acceptable…
Thanks for your effort
To get valid results and to tell if it’s a Wi-Fi or MQTT Problem, I activated a ping from Home Assistant, every 10 seconds.
An hour later I changed to uptime kurma, to get better statistics.
And now, there haven’t been any disconnects since then. Two disconnects around 3 a.m. for 1 second. But this could have been the Wi-Fi channel change too.
I’m not sure if it’s the Wi-Fi connection itself or in some way Nukis Wi-Fi connection, which is kept alive by this ping. Or maybe there was another change/update I haven’t recognized (don’t think so).
But for the last 10 - 12 hours it was stable. And that is a really big change since it disconnected at least 1-3 times an hour before.
@spanzetta maybe try also a ping to see if this fixes your disconnect problems. HA ping Integration sends a ping every 30 seconds, which should be enough.
I’m using an SDN with TP-Link Omada. The nuki is connected to an EAP225. But other devices don’t show this disconnect behavior or I don’t recognize it, cause it doesn’t matter so much to be connected constantly without any delay.
But the ESP Bridge was connected to the same EAP and had only the Bluetooth delay, I think. 
Never mind. I’m really happy, at the moment. Maybe a ping could be a workaround or at least a hint of a solution.
Update:
It worked for more than 24 hours without a reconnect. Then I changed the ping to 60 seconds and got a downtime again.
Now, with a ping every 30 seconds, it kept alive. Not sure how this is draining the battery, but it works. 
Since yesterday morning, I cannot use the Android app to use my smart lock if not connected to the smart lock by Blue Tooth.
MQTT works correctly, only remote actions using the Nuki app are not possible.
I tried to unplug/plug the battery with no change.
When I check in the app in integration section then Nuki Web near my smart lock it shows the smart lock is connected to my Nuki Web account.
Is someone facing the same issue?
EDIT: it becomes available again two days ago but this morning it occured again.
It looks cold weather is the only common point I see but I don’t remind I had the same issue last year.
I also had to re calibrate my smart lock this morning, it looks it occurs more often.
With this latest beta FW auto unlock feature stopped working…
Anyone else with same problem?
Nop.
But I notice some strangeness E.G. smart not calibrated anymore sometimes and it is fixed when unplugging and plugging again the battery.
I had not this with previous firmware but difficult to know if it is this version, even if last time it occurred, temperature was not so cold, 8°C outside just behind the door.
Hi there! How do you Ping the lock over MQTT exactly? I just dont get it to work…
I don’t do it over mqtt.
I use Home Assistant and there the ping integration (Ping (ICMP) - Home Assistant), to keep the nuki / wifi connection awake.
Ahh okay i See, do you put in the IP-Adress of the Nuki that is displayed in the Nuki App?
Like that?
alias: Nuki Ping
description: “”
trigger:
I looked up the IP in my router. And for a ping every 30 seconds, you don’t need a separate automation. 30 seconds is the default pooling interval.
Your automation is almost correct. You want to ping it every 30 seconds not at :30
alias: ping nuki
description: ""
trigger:
- platform: time_pattern
seconds: /20
condition: []
action:
- service: homeassistant.update_entity
target:
entity_id: binary_sensor.172_23_107_31
data: {}
mode: single
would ping every 20 seconds. The difference is the /
Perfect, thank you! 
Original post has been updated with release notes for the Smart Lock 3.0 Beta 3.8.4
This Beta is not including any user visible changes, but is still improving some code which pays into the overall system stability.
Please install this beta and provide your feedback via this channel - thank you!
I got the notification for the 3.8.4 beta today but the app (iOS) crashes in the step where it transfers the firmware to the Nuki.
Everything else is OK, I just can’t install the new firmware.
After installing this update, I still have connections issues with Nuki web, I’ve tried to open Nuki Android app and my smart lock is offline even if MQTT is OK.
Weather is definitely not the cause.