Ok, my mistake here...
My testing environment is a VirtualBox Server and clients, the server with 2 ethernet interfaces. My mistake here is that I was letting virtualbox setup the eth1 here with another DHCP from an internal (virtual) network...
Now, disabling this VrtualBox dhcp but maintaining the virtual network, the eth1 interface is gets an ip that I reconfigure like this:
$ sudo ifconfig eth1 192.168.56.101 netmask 255.255.255.0 up
The server is surfing the web after Terminal Server has started now (thanks), only the clients are still not surfing...