enable routing between LANs DrayTek Vigor 3900

I am assuming that the 'enable routing between LANs' on the  DrayTek Vigor 3900 is about routing traffic between VLANs on the system, but how does it work, what is the point of having different VLANs if I cannot choose what routes where and will the DHCP servers conflict using this feature?

I have one server I wish to access all VLANs but no other other interaction - is this possible?

The best option here is to use the firewall in conjunction with the different VLANS and LANS etc. The system is laid out nicely - once you define a VLAN then it is treated in exactly the same way as any other LAN or network gement. You can route between the different networks from various IPs and ports with subsequent rules that depend on each other and vice-versa using the rule system. In your case you will want to block all from one VLAN to the LAN with the exception of the machine in question. Make sure you allow communication in both directions otherwise the system will not work correctly, but lock both directions down to just that machine and port number or socket.