Yes, if you check your call & data filters you'll find netbios is blocked LAN->WAN by default on the 2820.

I did set that filter to pass the firewall when it was turned on

how are the 192.168.0.* machines supposed to resolve the netbios names on the 192.168.1.* network ? I didn't think the dreaded netbios master browser system routes.

I take it you have a 255.255.255.0 netmask ?

Yes true, as a horrible bodge you could edit the hosts file on the PCs and make sure they are allocated the same address each time....

yep thats what im doing as a fix for now with the hosts file, not to worry to much as intend to migrate all machines over eventualy its just not possible right now.

All machines are on the 255.255.255.0 subnet yes

You might think Draytek would at least appoint someone to look at these forums and help out though!!
Cheers