FireQOS: need help with input traffic shaping

Hi,

I already spend hours on reading and testing tc.
But now I'm at a point where I have to ask here for any hints.

Basically I want to shape my input and output traffic.
I have one nas server which handles large downloads. I want that nas to 
have a low priority, so that if I start a download on a normal client in 
the network this client gets most of the bandwidth.
But I cant get this to work. Here is my fireqos.conf:
####################################
DEVICE=eth0
INPUT_SPEED=14300kbit
OUTPUT_SPEED=2400kbit
LINKTYPE="adsl remote bridged-llc mtu 1492"

interface $DEVICE dsl-in input rate $INPUT_SPEED $LINKTYPE qdisc htb
     # Eingehender Traffic Internet --> LAN
     class interactive commit 1000kbit
         match udp port 53                    # DNS
         match tcp port 22                    # SSH
         match icmp

     class tcpack commit 2000kbit
         match tcp syn
         match tcp ack
         match tcp acks

     class web-http commit 7500kbit
         match tcp sports 80,443    prio 20         # http(s)

     class default commit 2500kbit

     class lowprio commit 1% max 80% prio 7
         match4 dst 192.168.2.11 prio 10        # debsrv


interface $DEVICE dsl-out output rate $OUTPUT_SPEED $LINKTYPE qdisc htb
     # Ausgehender Traffic LAN --> Internet
     class interactive commit 200kbit
         match udp port 53                    # DNS
         match tcp port 22                    # SSH
         match icmp

     class tcpack commit 400kbit
         match tcp syn
         match tcp ack
         match tcp acks

     class web-http commit 1100kbit
         match tcp dports 80,443 prio 20        # http(s)

     class default commit 600kbit

     class lowprio commit 1% max 80% prio 7
         match4 src 192.168.2.11 prio 10     # debsrv
####################################

If I now start downloading on both hosts with e.g. wget 
http://cdimage.debian.org/debian-cd/7.8.0/amd64/iso-dvd/debian-7.8.0-amd64-DVD-2.iso 

I get the following stats:


Class Utilization on dsl-in (eth0 input => eth0-ifb) - values in Kbit/s
  TOTAL intera tcpack web-ht defaul lowpri
  14552      -      - 6069 3   8480
  14116 1      -   5418      -   8697
  14139      -      - 6011 1   8127
  14422      -      -   6078      -   8344
  14281      -      -   5299      -   8982
  14264      3      -   5521      -   8739
  14277      -      -   5252      1   9024
  14201      -      -   4798      1   9403
  14288      -      -   4762      1   9525
  14227      -      -   4988      -   9253
  14293      -      -   6318     11   7951
  14327      -      -   6905    142   7281
  14219      -      -   6988      -   7232
  14133      -      -   7172      -   6960
  14347      -      -   7196      -   7151
  14390      -      -   7048      1   7340
  14203      1      -   7024      1   7177
  14289      1      -   6979      -   7309
  14272      1      4   6852     12   7403
  14304      3      -   6385      -   7916

==> lowprio is getting much more bandwidth... why?
Can anyone help me out / explain why it is behaving like this?

Outgoing everything works like expected.
(Used scp to upload a file to remote server)

  Class Utilization on dsl-out (eth0 output => eth0) - values in Kbit/s
  TOTAL intera tcpack web-ht defaul lowpri
   2674   2619      -     28      -     27
   2432   2379      -     25      -     27
   2524   2483      -     14      -     27
   2515   2462      -     25      -     27
   2527   2490      -     24      -     14
   2501   2458      -     14      1     27
   2520   2476      -     17      -     27
   2551   2509      -     14      -     27
   2514   2463      -     25      -     27
   2532   2479      -     25      1     27
   2514   2474      -     13      -     27
   2512   2469      2     27      1     14
   2531   2323     70     25     86     27
   2546   2490      -     29      -     27
   2505   2463      -     15      -     27
   2534   2479      1     25      1     27
   2519   2440      -     52      -     27
   2550   2491      -     31      -     27
   2511   2476      -     22      -     14
   2511   2449      5     22      7     27

Thanks!

Regards
Andreas