The clock is running now for around two weeks in real life scenario meaning mounted in clock hole of house and clock hands are ouside.

It runs smoothly - nearly perfect - but with one huge issue: at midnight it changes the time and goes back one hour. This happens only at first day midnight after power on and next days it still has got same time difference of -1 hour unchanged.

I first thought it is a mechanical problem but it is not! So the NTP time goes wrong from midnight. I can see NTP time on display and in web interface. It is a software issue only.

So I decided to put same software version on another ESP-01 just for testing. And now for around a week no issue there. Time is perfect no jumping back once. Crazy!

I also gave code to two other software developers and they could not find the bug which might be in NTP library I am using: https://github.com/sstaub/NTP

So what are the differences now:

- asking once a minute for time triggered from serial and doing  ntp.update(); it loses one hour at first midnight

- asking once a second for time it should work. If have not tested it but it is the example from NTP lib

- just running and asking for time only a few times a day it is also working (separate ESP)

So I cannot make a ticket for that library on Github because in test it just works and it would be impossible to reproduce for anybody else.