Today i can say :DS3231 working prefect. If raspberry pi lost internet connection time is allways right. How i connect this arduino module and set up i write if it is interesting. Sorry only my English. My mother tongue is Estonian
I do nat have a RTC, but did order one, shoud be comming in the mail soon.
Thinking about the technical part, I do think that it has all to do with the Raspberry and nothing to do with the rest of the software.
Just like a PC, that does have an RTC, this should never effect the software (other than the time being set).
And for last. We need show hardware clock time
#sudo hwclock --show
if it shows UTC time and you need set it to localtime
#sudo hwclock --systohc --localtime
and save this
#sudo hwclock -s
and watching time with
#sudo hwclock -r