wireless disconnection problem with rb2011

RouterOS Wireless Networking
1

hey everyone
we have a routerboard-2011ah installed in the second floor of a department . the problem is that after a while users disconnected from the network randomly .
we have set bellow configuration:
mode: ap bridge
band: 2GHz B/G/N
channel width: 20/40MHz HT above
frequency: auto
wireless protocol: 802.11
Bridge mode: disable
and default authentication and default forward are checked.

we have test all of the channel width mode and nothing happened .
any help or advice would be appreciated .
Best Regards

2

That Vx.x RouterOS upgrade your rb2011

3

There is no 2011 ah device.

Switch on detail logging on wifi and check the log to see what happened.

4

hey to all
we upgraded routerOS version to 6.22 . and the device give me a brief log

Nov/22/2014 04:55:03 wireless,debug wlan1: 78:6A:89:7B:82:18 in local ACL, accept
Nov/22/2014 04:55:39 wireless,debug wlan1: 18:1E:B0:B0:C2:19 attempts to associate
Nov/22/2014 04:55:39 wireless,debug wlan1: 18:1E:B0:B0:C2:19 not in local ACL, by default accept

Nov/22/2014 04:55:47 wireless,info wlan1: data from unknown device CC:C3:EA:07:78:F7, sent deauth
Nov/22/2014 04:55:47 wireless,debug wlan1: 78:7E:61:4C:C5:6A attempts to associate
Nov/22/2014 04:55:47 wireless,debug wlan1: 78:7E:61:4C:C5:6A not in local ACL, by default accept

Nov/22/2014 04:55:57 wireless,info CC:C3:EA:07:78:F7@wlan1: connected
Nov/22/2014 04:56:42 wireless,debug wlan1: 5C:51:4F:64:9C:F9 attempts to associate
Nov/22/2014 04:56:42 wireless,info 5C:51:4F:64:9C:F9@wlan1: reassociating
Nov/22/2014 04:56:42 wireless,info 5C:51:4F:64:9C:F9@wlan1: disconnected, ok
Nov/22/2014 04:56:42 wireless,debug wlan1: 5C:51:4F:64:9C:F9 in local ACL, accept
Nov/22/2014 04:56:42 wireless,info 5C:51:4F:64:9C:F9@wlan1: connected
Nov/22/2014 04:57:18 wireless,info 4C:B1:99:ED:E8:38@wlan1: disconnected, received disassoc: sending station leaving (8)
Nov/22/2014 04:57:18 wireless,info wlan1: data from unknown device 4C:B1:99:ED:E8:38, sent deauth
Nov/22/2014 04:57:41 wireless,debug debug: wlan1: 18:1E:B0:B0:C2:19 attempts to associate
Nov/22/2014 04:57:41 wireless,info debug: 18:1E:B0:B0:C2:19@wlan1: reassociating
Nov/22/2014 04:57:41 wireless,info debug: 18:1E:B0:B0:C2:19@wlan1: disconnected, ok
Nov/22/2014 04:57:41 wireless,debug debug: wlan1: 18:1E:B0:B0:C2:19 not in local ACL, by default accept
Nov/22/2014 04:57:41 wireless,info debug: 18:1E:B0:B0:C2:19@wlan1: connected
Nov/22/2014 04:58:15 wireless,debug wlan1: 8C:FA:BA:63:3D:2F attempts to associate

any one have a solution ?
Best Regards