Hello Claudio Pelosi1,
Thank you for posting in Microsoft Community forum.
Based on the description "If I change the password via the web it is not synchronized in the local domain.":
Please check if you change password via the web successfully?
How did you check the password is not ***synchronized in the local domain?***Please check if the password is synchronized in the Azure domain.
Please check if any ports between Azure domain and local domain are open.
I hope the information above is helpful.
If you have any question or concern, please feel free to let us know.
Best Regards,
Daisy Zhou