timedatectl list-timezones
sudo timedatectl set-timezone Asia/Tehran
Check if time is correct :
date
Set to UTC
sudo dpkg-reconfigure tzdata
References
https://linuxconfig.org/how-to-change-timezone-on-ubuntu-18-04-bionic-beaver-linux
https://www.cyberciti.biz/faq/howto-set-date-time-from-linux-command-prompt/
https://askubuntu.com/questions/138423/how-do-i-change-my-timezone-to-utc-gmt