Why can't clients connect to DWL-3200AP?

Question

DHCP

Greetings, comrades!
There was a following problem. New clients periodically fail to connect to the point.
Model Name DWL-3200AP
Firmware Version v2.58RU
The problem occurs both with new clients and with existing ones. Clients cannot connect and get an IP address from a DHCP server on the network.
The point is assigned a stat. the address. and WiFi is up, Authentication is WPA2-Personal. DHCP - disabled at the point, that is, it works just like a switch, addresses are issued by a server on the network.
When you try to connect, the address is not issued and the connection hangs on initialization. In the logs we see the following:

WED DEC 09 12:29:58 2015   Wireless   --WLAN1 aged 11G STA 84:7a:88:0d:cf:e5
WED DEC 09 12:31:31 2015   Wireless   --Association:11G STA 18:f4:6a:13:48:e2 associated with WLAN1 SSID = ABK-1 
WED DEC 09 12:31:58 2015   Wireless   --Received Disassoc: WLAN 1 11G STA 18:f4:6a:13:48:e2 
WED DEC 09 12:31:58 2015   Wireless   --Received Deauth: WLAN 1 11G STA 18:f4:6a:13:48:e2 reason code=3
WED DEC 09 12:32:11 2015   Wireless   --Association:11G STA 18:f4:6a:13:48:e2 associated with WLAN1 SSID = ABK-1 
WED DEC 09 12:32:27 2015   Wireless   --Received Disassoc: WLAN 1 11G STA 18:f4:6a:13:48:e2 
WED DEC 09 12:32:27 2015   Wireless   --Received Deauth: WLAN 1 11G STA 18:f4:6a:13:48:e2 reason code=3
WED DEC 09 12:32:39 2015   Wireless   --Association:11G STA 18:f4:6a:13:48:e2 associated with WLAN1 SSID = ABK-1 
WED DEC 09 12:32:54 2015   Wireless   --Received Disassoc: WLAN 1 11G STA 18:f4:6a:13:48:e2 
WED DEC 09 12:32:54 2015   Wireless   --Received Deauth: WLAN 1 11G STA 18:f4:6a:13:48:e2 reason code=3

I found the decryption of code = 3, but I couldn’t figure out what the problem was.
If the point is turned off and on, then new clients connect normally. But after a day and a half of work, everything repeats again. The old ones seem to work, but the new ones cannot connect and you have to reboot the point again. I tried to force the channels to be different, nothing helps. But if you manually register the IP address on the device that connects, it will connect and everything will work fine. But for some reason it does not receive dhcp until you load the point. At the time of the problem, the point responds normally, I also go to the web face normally.

Answer 1

clients with static IP are connected?
traffic comes from them?
is the point visible from the wired segment?
Are VLANs configured on the point/switch?
it would not be superfluous to look at tcpdump on the dhcp server for packets from the desired MAC