1. mysqld.cnf
bind-address = 0.0.0.0
2. mysql:
create user 'admin'@'%' identified by 'my-password';
GRANT ALL PRIVILEGES ON *.* TO 'admin'@'%';
3. if ufw exists ufw allow mysql (3306/tcp) https://www.youtube.com/watch?v=DjUD7_mJJPE