Yesterday evening I changed the SSID and password on the 2.4 GHz radio to fix a tasmota device configured for a previous setup. At 22:02 I changed it back to the new SSID:
Jul 29 19:58:23 ap-lsys-cc hostapd: wlan0: STA 5c:cf:7f:xx:xx:xx IEEE 802.11: authenticated
Jul 29 19:58:23 ap-lsys-cc hostapd: wlan0: STA 5c:cf:7f:xx:xx:xx IEEE 802.11: associated (aid 1)
Jul 29 19:58:23 ap-lsys-cc hostapd: wlan0: AP-STA-CONNECTED 5c:cf:7f:xx:xx:xx
Jul 29 19:58:23 ap-lsys-cc hostapd: wlan0: STA 5c:cf:7f:xx:xx:xx RADIUS: starting accounting session DB4D77548F26F79D
Jul 29 19:58:23 ap-lsys-cc hostapd: wlan0: STA 5c:cf:7f:xx:xx:xx WPA: pairwise key handshake completed (RSN)
Jul 29 19:58:23 ap-lsys-cc hostapd: wlan0: EAPOL-4WAY-HS-COMPLETED 5c:cf:7f:xx:xx:xx
Jul 29 20:02:09 ap-lsys-cc hostapd: wlan0: STA f8:cf:c5:xx:xx:xx IEEE 802.11: authenticated
Jul 29 20:02:09 ap-lsys-cc hostapd: wlan0: STA f8:cf:c5:xx:xx:xx IEEE 802.11: associated (aid 2)
Jul 29 20:02:09 ap-lsys-cc hostapd: wlan0: AP-STA-CONNECTED f8:cf:c5:xx:xx:xx
Jul 29 20:02:09 ap-lsys-cc hostapd: wlan0: STA f8:cf:c5:xx:xx:xx RADIUS: starting accounting session E83E62E81DE81FD6
Jul 29 20:02:09 ap-lsys-cc hostapd: wlan0: STA f8:cf:c5:xx:xx:xx WPA: pairwise key handshake completed (RSN)
Jul 29 20:02:09 ap-lsys-cc hostapd: wlan0: EAPOL-4WAY-HS-COMPLETED f8:cf:c5:xx:xx:xx
Jul 29 20:08:51 ap-lsys-cc hostapd: wlan1: AP-STA-DISCONNECTED 24:a0:74:xx:xx:xx
Jul 29 20:08:51 ap-lsys-cc hostapd: wlan1: STA 24:a0:74:xx:xx:xx IEEE 802.11: authenticated
Jul 29 20:08:51 ap-lsys-cc hostapd: wlan1: STA 24:a0:74:xx:xx:xx IEEE 802.11: associated (aid 1)
Jul 29 20:08:51 ap-lsys-cc hostapd: wlan1: AP-STA-CONNECTED 24:a0:74:xx:xx:xx
Jul 29 20:08:51 ap-lsys-cc hostapd: wlan1: STA 24:a0:74:xx:xx:xx RADIUS: starting accounting session 28945744EBB4563A
Jul 29 20:08:51 ap-lsys-cc hostapd: wlan1: STA 24:a0:74:xx:xx:xx WPA: pairwise key handshake completed (RSN)
Jul 29 20:08:51 ap-lsys-cc hostapd: wlan1: EAPOL-4WAY-HS-COMPLETED 24:a0:74:xx:xx:xx
Jul 29 20:34:32 ap-lsys-cc hostapd: wlan1: AP-STA-DISCONNECTED 24:a0:74:xx:xx:xx
Jul 29 20:34:32 ap-lsys-cc hostapd: wlan1: STA 24:a0:74:xx:xx:xx IEEE 802.11: disassociated due to inactivity
Jul 29 20:34:33 ap-lsys-cc hostapd: wlan1: STA 24:a0:74:xx:xx:xx IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
Jul 29 20:40:10 ap-lsys-cc hostapd: wlan0: AP-STA-DISCONNECTED 5c:cf:7f:xx:xx:xx
Jul 29 20:40:10 ap-lsys-cc hostapd: wlan0: STA 5c:cf:7f:xx:xx:xx IEEE 802.11: disassociated due to inactivity
Jul 29 20:40:11 ap-lsys-cc hostapd: wlan0: STA 5c:cf:7f:xx:xx:xx IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
Jul 29 21:03:07 ap-lsys-cc hostapd: nl80211: kernel reports: key addition failed
Jul 29 21:03:07 ap-lsys-cc hostapd: wlan1: STA 24:a0:74:xx:xx:xx IEEE 802.11: associated (aid 1)
Jul 29 21:03:07 ap-lsys-cc hostapd: wlan1: AP-STA-CONNECTED 24:a0:74:xx:xx:xx
Jul 29 21:08:01 ap-lsys-cc hostapd: wlan1: AP-STA-DISCONNECTED 18:3e:ef:xx:xx:xx
Jul 29 21:08:01 ap-lsys-cc hostapd: wlan1: STA 18:3e:ef:xx:xx:xx IEEE 802.11: disassociated due to inactivity
Jul 29 21:08:02 ap-lsys-cc hostapd: wlan1: STA 18:3e:ef:xx:xx:xx IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
Jul 29 21:31:53 ap-lsys-cc hostapd: wlan1: STA 18:3e:ef:xx:xx:xx IEEE 802.11: authenticated
Jul 29 21:31:53 ap-lsys-cc hostapd: wlan1: STA 18:3e:ef:xx:xx:xx IEEE 802.11: associated (aid 2)
Jul 29 21:31:53 ap-lsys-cc hostapd: wlan1: AP-STA-CONNECTED 18:3e:ef:xx:xx:xx
Jul 29 21:31:53 ap-lsys-cc hostapd: wlan1: STA 18:3e:ef:xx:xx:xx RADIUS: starting accounting session 4139BD7DB31902DE
Jul 29 21:31:53 ap-lsys-cc hostapd: wlan1: STA 18:3e:ef:xx:xx:xx WPA: pairwise key handshake completed (RSN)
Jul 29 21:31:53 ap-lsys-cc hostapd: wlan1: EAPOL-4WAY-HS-COMPLETED 18:3e:ef:xx:xx:xx
Jul 29 22:02:06 ap-lsys-cc kernel: [75805.147336] device wlan0 left promiscuous mode
Jul 29 22:02:06 ap-lsys-cc kernel: [75805.151862] br-lan: port 3(wlan0) entered disabled state
Jul 29 22:02:06 ap-lsys-cc hostapd: Remove interface 'wlan0'
Jul 29 22:02:06 ap-lsys-cc hostapd: wlan0: interface state ENABLED->DISABLED
Jul 29 22:02:06 ap-lsys-cc hostapd: wlan0: AP-STA-DISCONNECTED f8:cf:c5:xx:xx:xx
Jul 29 22:02:06 ap-lsys-cc hostapd: wlan0: AP-DISABLED
Jul 29 22:02:06 ap-lsys-cc hostapd: wlan0: CTRL-EVENT-TERMINATING
Jul 29 22:02:06 ap-lsys-cc hostapd: rmdir[ctrl_interface=/var/run/hostapd]: Permission denied
Jul 29 22:02:06 ap-lsys-cc hostapd: nl80211: deinit ifname=wlan0 disabled_11b_rates=0
Jul 29 22:02:06 ap-lsys-cc hostapd: nl80211: Failed to remove interface wlan0 from bridge br-lan: Invalid argument
Jul 29 22:02:06 ap-lsys-cc netifd: Network device 'wlan0' link is down
Jul 29 22:02:06 ap-lsys-cc hostapd: Configuration file: /var/run/hostapd-phy0.conf (phy wlan0) --> new PHY
Jul 29 22:02:06 ap-lsys-cc netifd: Network device 'wlan0' link is up
Jul 29 22:02:06 ap-lsys-cc netifd: Network device 'wlan0' link is down
Jul 29 22:02:06 ap-lsys-cc kernel: [75805.648284] br-lan: port 3(wlan0) entered blocking state
Jul 29 22:02:06 ap-lsys-cc kernel: [75805.653613] br-lan: port 3(wlan0) entered disabled state
Jul 29 22:02:06 ap-lsys-cc kernel: [75805.659227] device wlan0 entered promiscuous mode
Jul 29 22:02:06 ap-lsys-cc kernel: [75805.664065] br-lan: port 3(wlan0) entered blocking state
Jul 29 22:02:06 ap-lsys-cc kernel: [75805.669482] br-lan: port 3(wlan0) entered listening state
Jul 29 22:02:06 ap-lsys-cc hostapd: wlan0: interface state UNINITIALIZED->COUNTRY_UPDATE
Jul 29 22:02:07 ap-lsys-cc netifd: Network device 'wlan0' link is up
Jul 29 22:02:07 ap-lsys-cc hostapd: wlan0: interface state COUNTRY_UPDATE->ENABLED
Jul 29 22:02:07 ap-lsys-cc hostapd: wlan0: AP-ENABLED
Jul 29 22:02:07 ap-lsys-cc kernel: [75805.727138] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
Jul 29 22:02:09 ap-lsys-cc kernel: [75807.725775] br-lan: port 3(wlan0) entered learning state
Jul 29 22:02:11 ap-lsys-cc kernel: [75809.805778] br-lan: port 3(wlan0) entered forwarding state
Jul 29 22:02:11 ap-lsys-cc kernel: [75809.811270] br-lan: topology change detected, sending tcn bpdu
Jul 29 22:13:48 ap-lsys-cc kernel: [76507.624097] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000053
There is nothing in the logs after the already posted Oops line until I manually restarted the device at 11 AM this morning.