Here is an example log between ChkWAN disconnects and reconnects:
Dec 25 23:17:02 (ChkWAN.sh): 32317 Monitoring WAN connection OK.....(Successful ping to '8.8.8.8'); Terminating due to ACTIVE cron schedule
Dec 25 23:18:02 (ChkWAN.sh): 32545 v1.15 Monitoring WAN connection using 2 target PING hosts (8.8.8.8 8.8.4.4) (Tries=1)
Dec 25 23:18:02 (ChkWAN.sh): 32545 Monitoring pass 1 out of 1
Dec 25 23:18:05 (ChkWAN.sh): 32545 v1.15 Monitoring WAN connection using PING method to 8.8.8.8 check FAILED
Dec 25 23:18:08 (ChkWAN.sh): 32545 v1.15 Monitoring WAN connection using PING method to 8.8.4.4 check FAILED
Dec 25 23:18:08 (ChkWAN.sh): 32545 Renewing DHCP and restarting WAN (Action=WANONLY)
Dec 25 23:18:18 rc_service: service 32735:notify_rc restart_wan
Dec 25 23:18:18 dnsmasq[481]: read /etc/hosts - 7 addresses
Dec 25 23:18:18 dnsmasq[481]: read /etc/hosts.dnsmasq - 1 addresses
Dec 25 23:18:18 dnsmasq[481]: using nameserver 1.0.0.1#53
Dec 25 23:18:18 dnsmasq[481]: using nameserver 1.1.1.1#53
Dec 25 23:18:19 dnsmasq[481]: read /etc/hosts - 7 addresses
Dec 25 23:18:19 dnsmasq[481]: read /etc/hosts.dnsmasq - 1 addresses
Dec 25 23:18:19 dnsmasq[481]: using nameserver 1.0.0.1#53
Dec 25 23:18:19 dnsmasq[481]: using nameserver 1.1.1.1#53
Dec 25 23:18:19 WAN_Connection: ISP's DHCP did not function properly.
Dec 25 23:18:20 DualWAN: skip single wan wan_led_control - WANRED off
Dec 25 23:18:23 kernel: br0: port 1(vlan1) entering forwarding state
Dec 25 23:18:23 kernel: LACP lacp_proc_exit(298): MSG:lacp all Proc Entry Removed!
Dec 25 23:18:23 kernel: LACP fsm_deinit(1655): MSG:Port 2 uninitialize
Dec 25 23:18:23 kernel: LACP fsm_deinit(1655): MSG:Port 3 uninitialize
Dec 25 23:18:24 kernel: device eth0 left promiscuous mode
Dec 25 23:18:24 kernel: br1: port 2(eth0.501) entering forwarding state
Dec 25 23:18:24 kernel: device eth0 entered promiscuous mode
Dec 25 23:18:24 kernel: br0: topology change detected, propagating
Dec 25 23:18:24 kernel: br0: port 1(vlan1) entering forwarding state
Dec 25 23:18:24 kernel: br0: port 1(vlan1) entering forwarding state
Dec 25 23:18:24 kernel: ### LACP: Jun 21 2020 01:59:53 version 7.14.164.303 (r666427)
Dec 25 23:18:24 kernel: LACP fsm_get_lacp_ports_config(1484): MSG:lacpports 2 3
Dec 25 23:18:24 kernel: LACP fsm_init(1585): MSG:fsm_info->ports_mask 0xc
Dec 25 23:18:24 kernel: LACP fsm_init(1595): MSG:Port 2 initialize
Dec 25 23:18:24 kernel: LACP fsm_init(1595): MSG:Port 3 initialize
Dec 25 23:18:24 kernel: LACP fsm_init(1622): MSG:lastport 3
Dec 25 23:18:24 kernel: LACP lacp_proc_init(277): MSG:lacp_msg_level 0x0
Dec 25 23:18:24 kernel: LACP lacp_proc_init(279): MSG:lacp created
Dec 25 23:18:24 kernel: br1: port 2(eth0.501) entering listening state
Dec 25 23:18:24 kernel: br1: port 2(eth0.501) entering listening state
Dec 25 23:18:24 dnsmasq[481]: read /etc/hosts - 7 addresses
Dec 25 23:18:24 dnsmasq[481]: read /etc/hosts.dnsmasq - 1 addresses
Dec 25 23:18:24 dnsmasq[481]: using nameserver 1.0.0.1#53
Dec 25 23:18:24 dnsmasq[481]: using nameserver 1.1.1.1#53
Dec 25 23:18:26 dnsmasq[481]: read /etc/hosts - 7 addresses
Dec 25 23:18:26 dnsmasq[481]: read /etc/hosts.dnsmasq - 1 addresses
Dec 25 23:18:26 dnsmasq[481]: using nameserver 1.0.0.1#53
Dec 25 23:18:26 dnsmasq[481]: using nameserver 1.1.1.1#53
Dec 25 23:18:26 wan: finish adding multi routes
Dec 25 23:18:26 start_ddns: update WWW.ASUS.COM update@asus.com, wan_unit 0
Dec 25 23:18:27 inadyn[900]: In-a-dyn version 2.7 -- Dynamic DNS update client.
Dec 25 23:18:29 inadyn[900]: Update forced for alias xxxxxxxxxx.asuscomm.com, new IP# xxx.xxx.xxx.xxx
Dec 25 23:18:30 inadyn[900]: Updating cache for xxxxxxxxxx.asuscomm.com
Dec 25 23:18:30 WAN_Connection: WAN was restored.
Dec 25 23:18:30 dnsmasq[481]: read /etc/hosts - 7 addresses
Dec 25 23:18:30 dnsmasq[481]: read /etc/hosts.dnsmasq - 1 addresses
Dec 25 23:18:30 dnsmasq[481]: using nameserver 1.0.0.1#53
Dec 25 23:18:30 dnsmasq[481]: using nameserver 1.1.1.1#53
Dec 25 23:18:39 kernel: br1: port 2(eth0.501) entering learning state
Dec 25 23:18:47 BWDPI: fun bitmap = 3
Dec 25 23:18:48 dhcp_client: bound xxx.xxx.xxx.xxx/255.255.254.0 via xxx.xxx.xxx.xxx for 172800 seconds.
Dec 25 23:18:54 kernel: br1: topology change detected, propagating
Dec 25 23:18:54 kernel: br1: port 2(eth0.501) entering forwarding state
Dec 25 23:19:02 (ChkWAN.sh): 1426 v1.15 Monitoring WAN connection using 2 target PING hosts (8.8.8.8 8.8.4.4) (Tries=1)
Dec 25 23:19:02 (ChkWAN.sh): 1426 Monitoring pass 1 out of 1
Dec 25 23:19:02 (ChkWAN.sh): 1426 Monitoring WAN connection OK.....(Successful ping to '8.8.8.8'); Terminating due to ACTIVE cron schedule