Webmin is only run locally until the user opens port 1000 in the router/firewall, so no outside access. phpMyadmin is there to make it easier to administer databases (obvious) and access is forbidden ...

--** By the way – This is just a setting from Administration > Preferences menu which we are modifying via SQL because our BackOffice connection is broken and this value won’t be saved from admin ...

When you start administering a Linux system, one of the biggest challenges is learning exactly what to do, and how to do it. There simply are too many tools, settings, parameters, configuration files, ...