[Sussex] Draytek router configuration

[Al Bennett]

Evening all

OK, so I've acquired a Draytek 2800G ADSL router which looks the part but 
actually seems to be pretty crappy.  I'm trying to find out how best to set 
the damn thing up to do what I want it to, so if anyone has any experience 
with Draytek routers I'd appreciate some pointers!

What I'm trying to set up is a simple network of two Windows NATted PCs 
which receive IPs via DHCP from the router and a Debian server which has a 
static IP.  We've got 5 usable IPs from Zen Internet and I'd like one of 
them to go to the Debian box but that box still to be accessible from the 
two windows PCs (my first attempt at setting this up had full access for the 
server but no way to talk to the different subnets).

To me this seems simple enough for a £160 router to handle but for the life 
of me I can't get it all working.  I've got it to the point now where the 
PCs get IPs and happily chat to each other, I've assigned a private IP to 
the server (in the 192.168.1.xxx range) and now PCs and server talk (I 
think, not very well tested).

What I can't get to work is the external IP address forwarded to the 
internal server address.  I've presently got it set up using some form port 
forwarding but it seems to work unreliably.  Sometimes I can connect using 
the external IP, sometimes not.

Does anyone have any idea how I should be doing this and if I'm at all near 
the mark?

TIA!

Al