I think the mysql root user password is wrong. Nethserver stores passwords in /var/lib/nethserver/secrets/. To reset the mysql root password please follow these steps:
Get the password of mysql root:
cat /var/lib/nethserver/secrets/mysql
Reset root password, replace SECRET with the password you got in previous step.
systemctl stop mysqld
mysqld_safe --skip-grant-tables &
mysql mysql
update user set password=PASSWORD("SECRET") where User='root';
flush privileges;
exit
mysqladmin shutdown
systemctl start mysqld
http://docs.nethserver.org/projects/nethserver-devel/en/v7/mysql.html
To reconfigure freepbx:
signal-event nethserver-freepbx-update
Just to compare rights/owner, maybe there’s a permission problem (too):
ll /var/www/html/
total 0
drwxrwxr-x 3 asterisk asterisk 54 Aug 10 20:17 freepbx