Why is the Internet cut off through a WiFi router?

Question

ASUS

Good afternoon.
The Internet periodically drops, which is distributed via WiFi and a separate cable from the router to the PC.
Router Asus RN-N16, firmware version 3.0.0.4.380_7378, reset to factory settings via the web did not help. Reset through the WPS button did not help.
When the Internet is turned off, a page appears in the browser with the text:

The settings have been changed. The web page will now be updated.
The IP address or port number has changed. You will now be disconnected from the RT-N16.
To access the RT-N16 settings, reconnect to the wireless network using the updated IP address or port number.

Rotary logs at the time of the fall of the Internet:

Mar 12 16:10:38 rc_service: ntp 489:notify_rc restart_upnp
Mar 12 16:10:38 miniupnpd[499]: shutting down MiniUPnPd
Mar 12 16:10:38 miniupnpd[509]: version 1.9 started
Mar 12 16:10: 38 miniupnpd[509]: HTTP listening on port 58717
Mar 12 16:10:38 miniupnpd[509]: Listening for NAT-PMP/PCP traffic on port 5351
Mar 12 16:10:38 rc_service: ntp 489:notify_rc restart_diskmon
Mar 12 16:10:38 disk_monitor: Finish
Mar 12 16:10:38 disk monitor: be idle
Mar 12 16:10:41 rc_service: zcip 521:notify_rc start_firewall
Mar 12 16:10:42 zcip client: configured 169.254.106.228
Mar 12 16:10:42 miniupnpd[509]: shutting down MiniUPnPd
Mar 12 16:10:42 start_nat_rules: apply the nat_rules(/tmp/nat_rules_ppp0_eth0)!
Mar 12 16:10:42 miniupnpd[544]: version 1.9 started
Mar 12 16:10:42 miniupnpd[544]: HTTP listening on port 50661
Mar 12 16:10:42 miniupnpd[544]: Listening for NAT-PMP/ PCP traffic on port 5351