Speed Issue

Hi all. Have some weard situation. Instal 2.4Ghz link over 4km. Everything would be okey, only speed is not i was expected. I assume speed should be >25Mbps but nop - all i get on Rx (UDP) is ~18Mbps and ~8Mbps on Tx. Any ideas? Even when AP is idle (noone, except me, connected) and signal is 54/54Mbps with CCQ >90%.

could you post the config?



 1  R name="Wlan1" mtu=1500 mac-address=00:13:46:98:23:68 arp=enabled 
      interface-type=Atheros AR5413 mode=station ssid="WaterTower" frequency=2427 
      band=2ghz-b/g channel-width=20mhz scan-list=default 
      wireless-protocol=unspecified antenna-mode=ant-a wds-mode=disabled 
      wds-default-bridge=none wds-ignore-ssid=no default-authentication=yes 
      default-forwarding=yes default-ap-tx-limit=0 default-client-tx-limit=0 
      hide-ssid=no security-profile=default compression=no