Hi robb
Thank you so much for your reply.
The way you visualize, should work provided you add a switch between the Zentyal server and the LAN. Also the way you point out, your VDSL modem is not only modem but also a router.
That is truth , but I don't wanna have my webserser inside my Lan. It is a security issue.
To be able to access the webserver from the internet, you need to forward port 80 on your VDSL modem/router to your webserver.
In reality I already have access to my webserver from the internet
If you need to access your Zentyal Webadmin page from the internet you either have to configure VPN and access it via the internal IP address, or forward the webadmin port (default 443) to your Zentyal server.
I need only get Zentyal's admin access from the Lan.
My real problem is workstations start get access from the Lan to the Webserver.
For a senario like that I was think in two possibilities:
1.Use of hosts files on each workstation to redirect to the webserver(192.168.24.1 my.web.server) or
2.An entry on DNS server at Zentyal box
I don't know which of the two will work, and I do not know how to get a entry on Zentyal's DNS