I have an ADSL Vigor 2600 (not the wireless one) firmware v2.3.2 MTU 1400. There were 4 computers running WinXP connected to it and everything worked fine, network and internet connection.

I have just added a new Vista Ultimate computer to the network. The computer connects to the network just fine and all the other computers can be 'seen'. The problem is with connecting to the internet. Initially, the connection says 'Local Only' (meaning network) and not connected to the internet. After a while a connection to the internet is somehow established, but most websites cannot be accessed - it just times out. One or two websites eg. baa.com is fine but others like microsoft are not. The computer is set to obtain IP address automatically.

I have tried disabling IPv6 and disabling DHCP broabcast in the registry, both of which I've heard can cause such a problem, but to no avail. The firmware was upgraded in February this year. There is a newer one but no mention is made of Vista in the release notes.

Just to add, this computer with the same settings worked without any problems when it was used on a network with a Netgear DG836PN router.

Are all your PCs getting their TCP/IP config from the Draytek using DHCP? If not and they are set manually check that everything on the network has the same subnet mask. On the Vista PC get a command prompt and run netstat -r (assuming this works on Vista) to see if it tells you anything useful.