I have a number of IP Address ranges and wanted to configure my 2830 to limit internet bandwidth to some of the IP Addresses.

My 2830 is in the 192.168.192.x range
I have some client in the 10.0.20.x range so I added a bandwidth limit to the 2830 for this range. A message was displayed that the range was outside the 2830 range but allowed me to add it anyway. I then tested from a 10.0.20.0 machine and bandwidth limitation was not working. I then tested a blanket bandwidth limit instead of IP specific so it should have affected all users - it only affected the 192.168.192.x users and not the 10.0.20.x users - if it had of worked I was then looking at adding unlimited bandwidth entries for the 192.168.192.x IP Addresses so thereby implementing what I wanted but using reverse login (limit all unlimit some instead of unlimit all limit some).

The routing of the 10.0.20.x traffic is through a Cisco Router but I don't see how this would affect the 2830. 2830 has a static route to the 10.0.20.x network via 192.168.192.253 (Cisco Router)

check this guide
http://www.draytek.com/index.php?option=com_k2&view=item&id=1827&Itemid=293&lang=en
Not sure if will work but also have you tried via Ip routed subnet in this menu?
As for the ip out of range have you tried first at bind ip to mac register one address of that range for testing to see if will accept it?

I have looked at Data Flow Monitor and no IP's in the 10.0.20.x range appear there but they do appear in the NAT Sessions.

I looked at IP Routing but that seemed to be disabling NAT and allowing public IP Addresses on your LAN - not something I am looking at doing.

I have looked at Bind IP to MAC but this seems to be for making a DHCP lease permanent. No 10.0.20.x addresses appear in here as the Draytek does not give out IP Addresses in this DHCP range - that is the job of the Cisco Router. I tried adding one but it comes up with a message that the IP Address is not in the 2830's range so can not be added.