Help needed with shaper policy

Hi All, I think I am getting myself all about face with this one and could use some help.

I am trying to set up a traffic shaper policy for the following setup.

LAN (10.20.0.5/24) --> VPN <-- LAN (192.168.128.1/22) <-- (192.168.128.2) ROUTER NAT (10.20.9.1) < -- LAN (10.20.9.0/24)

LAN 192.168.128.0/22 has an Edgerouter lite. What I am trying to accomplish is that traffic from 10.20.9.0/24 and 10.20.0.5/24 get priority over any other traffic. 192.168.128.0/22 is on eth0 and the Internet connection is on eth1

shaper Down {
   bandwidth 20Mbit
     class 2 {
        bandwidth 5Mbit
         burst 15k
         ceiling 100%
         match client2 {
             ip {
                 source {
                     address 10.20.9.0/24
                 }
             }
         }
         queue-type fair-queue
     }
     default {
         bandwidth 10mbit
         burst 15k
         ceiling 100%
         queue-type fair-queue
     }
 }
 shaper Up {
     bandwidth 2mbps
     class 2 {
         bandwidth 500kbps
         burst 15k
         ceiling 100%
         match client2 {
             ip {
                 source {
                     address 10.20.5.0/24
                 }
             }
         }
         queue-type fair-queue
     }
     default {
         bandwidth 1.5mbps
         burst 15k
         ceiling 100%
         queue-type fair-queue
     }
 }

 ethernet eth0 {
     address 192.168.128.1/22
     description Local
     duplex auto
     firewall {
         in {
         }
         out {
             name LAN_Controller
         }
     }
     speed auto
     traffic-policy {
         out Till-Down
     }
 }
 ethernet eth1 {
     address 82.XXX.XXX.238/30
     description Internet
     duplex auto
     firewall {
         in {
             name WAN_IN
         }
         local {
             name WAN_LOCAL
         }
         out {
             name LAN_Controller
         }
     }
     speed auto
     traffic-policy {
         out Till-Up
     }
 }
 loopback lo {
 }

The 10.20.9.0/24 network is NAT'd to the 192.168.128.0/22 network.

The above connection does not seem to be giving priority to the 10.20.X.X networks. Are the traffic policies applied to the right interfaces and of course are the policies right? Should I be using the NAT address for the source or as above in my config the actual address behind the NAT for shaping?

Last question, I promise. Everywhere I have looked people use the burst set at 15k but I cannot find the information on what this does. Is it burst above the defined limit for bandwidth?