5510 public IP block access

Hi there,<br/>
<br/>
We're using a 5510 (dual WAN setup) in our office and I'm having a problem accessing the other public IPs which are in the block allocated to us.<br/>
<br/>
Basically we have two connections each with 8 IPs, the draytek has one of each and we have a couple of other machines which are upstream of the draytek which also have public IPs. In particular I will use our other router as an example. This is a PC running Smoothwall linux firewall with Siproxd to act as a proxy for our IP phone system.<br/>
<br/>
The problem is as such, when using the draytek as my gateway I cannot get access to the public side of the Smoothwall, but when using the smoothwall as my gateway I <I>can</I> get access to the public side of the Draytek.<br/>
<br/>
It seems as if the draytek does not know how to route traffic to the other Public IPs in our block. If anyone knows how to solve this issue (it is a major pain) it would be very much appreciated.