Wifi Clients got disconnected from Sophos AP every x minutes

Hi i have a problem, i have a clean installation of XG (SFOS 17.0.5 MR-5).

All my Wifi clients got disconnected every x minutes. 

But why got the AP15 a new config? Nothing changed at this time.

When a client got disconnected/connected the AP15 get a new configuration, but why?

I have removed the AP already and reconfigured it again, removed power cable of course, too.

SYSTEM log from the night:

2018-03-07 04:57:52
DHCP Server
Renew
Lease IP 192.168.0.156 renewed for MAC 68:54:fd:xx:xx:xx
60020
SYSTEM
2018-03-07 04:57:45
DHCP Server
Renew
Lease IP 192.168.0.20 renewed for MAC 00:1a:8c:bxx:xx:xx
60020
SYSTEM
2018-03-07 04:57:42
DHCP Server
Renew
Lease IP 192.168.0.20 renewed for MAC 00:1a:8c:bxx:xx:xx
60020
SYSTEM
2018-03-07 04:57:40
Wireless Protection
Successfully sent config to AP [A40039B90D24xxx].
18007
SYSTEM
2018-03-07 04:54:43
DHCP Server
Renew
Lease IP 192.168.0.156 renewed for MAC 68:54:fd:xx:xx:xx
60020
SYSTEM
2018-03-07 04:54:30
DHCP Server
Renew
Lease IP 192.168.0.20 renewed for MAC 00:1a:8c:bxx:xx:xx
60020
SYSTEM
2018-03-07 04:54:26
DHCP Server
Renew
Lease IP 192.168.0.20 renewed for MAC 00:1a:8c:bxx:xx:xx
60020
SYSTEM
2018-03-07 04:54:25
Wireless Protection
Successfully sent config to AP [A40039B90D24xxx]
 

awed.log:

018-03-07 05:22:26 Use of uninitialized value $clientiplist in split at /</bin/awed>WP_connected_clients.pm line 917.
2018-03-07 05:22:26 1 WP_connected_clients::get_client_ip
2018-03-07 05:22:26 2 WP_connected_clients::check_lease
2018-03-07 05:22:26 3 WP_connected_clients::update_clients
2018-03-07 05:22:26 WARN -------------------------------------------------------

2018-03-07 22:01:09 [MASTER] new connection from 192.168.0.20:58468
2018-03-07 22:01:09 [A40039B90D24987] AP15 from 192.168.0.20:58468 identified as A40039B90D24xxx
2018-03-07 22:01:09 Could not read from file '/tmp/awed/A40039B90D24xxx.pid': No such file or directory
2018-03-07 22:01:09 [A40039B90D24xxx] (Re-)loaded identity and/or configuration
2018-03-07 22:01:14 [A40039B90D24xxx] ll_read: dead socket: Interrupted system call
2018-03-07 22:01:14 [A40039B90D24xxx] disconnected. Close socket and kill process.
2018-03-07 22:01:37 [MASTER] updating DB for AP A40039B90D24xxx with new channels (1 -> 9)
2018-03-07 22:03:40 [A40039B90D24xxx] ll_read: dead socket: Resource temporarily unavailable
2018-03-07 22:03:40 [A40039B90D24xxx] disconnected. Close socket and kill process.
2018-03-07 22:03:43 [MASTER] new connection from 192.168.0.20:58487
2018-03-07 22:03:43 [A40039B90D24xxx] AP15 from 192.168.0.20:58487 identified as A40039B90D24xxx
2018-03-07 22:03:43 Could not read from file '/tmp/awed/A40039B90D24xxx.pid': No such file or directory
2018-03-07 22:03:43 [A40039B90D24xxx] (Re-)loaded identity and/or configuration
2018-03-07 22:04:07 [MASTER] new connection from 192.168.0.20:58492

Please help! Thanks in advance.