Here is the log from when I connected to OpenVPN at 17:29:32, manually disconnected at 17:30:00 after no traffic was passing, until 17:30:28 when normal Internet connectivity was re-established.
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21983]: OpenVPN 2.4.3 mips-openwrt-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [MH/PKTINFO] [AEAD]
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21983]: library versions: OpenSSL 1.0.2k 26 Jan 2017, LZO 2.09
Tue Feb 26 17:29:32 2019 daemon.warn openvpn[21988]: WARNING: --ns-cert-type is DEPRECATED. Use --remote-cert-tls instead.
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: Outgoing Control Channel Authentication: Using 256 bit message hash 'SHA256' for HMAC authentication
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: Incoming Control Channel Authentication: Using 256 bit message hash 'SHA256' for HMAC authentication
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: TCP/UDP: Preserving recently used remote address: [AF_INET]127.0.0.1:3443
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: Socket Buffers: R=[87380->87380] S=[16384->16384]
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: Attempting to establish TCP connection with [AF_INET]127.0.0.1:3443 [nonblock]
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: TCP connection established with [AF_INET]127.0.0.1:3443
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: TCP_CLIENT link local: (not bound)
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: TCP_CLIENT link remote: [AF_INET]127.0.0.1:3443
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: NOTE: UID/GID downgrade will be delayed because of --client, --pull, or --up-delay
Tue Feb 26 17:29:32 2019 daemon.notice stunnel: LOG5[17]: Service [openvpn-stunnel] accepted connection from 127.0.0.1:40402
Tue Feb 26 17:29:32 2019 daemon.notice stunnel: LOG5[17]: s_connect: connected <REMOTESERVER>:443
Tue Feb 26 17:29:32 2019 daemon.notice stunnel: LOG5[17]: Service [openvpn-stunnel] connected remote server from 10.1.17.89:35910
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: TLS: Initial packet from [AF_INET]127.0.0.1:3443, sid=96b4d31e 0936202e
Tue Feb 26 17:29:32 2019 kern.info kernel: [ 5073.834827] eth1: link down
Tue Feb 26 17:29:32 2019 kern.info kernel: [ 5073.838063] br-lan: port 1(eth1) entered disabled state
Tue Feb 26 17:29:32 2019 daemon.notice netifd: Network device 'eth1' link is down
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: VERIFY OK: depth=1, CN=xxxx root CA
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: VERIFY OK: nsCertType=SERVER
Tue Feb 26 17:29:32 2019 daemon.notice openvpn[21988]: VERIFY OK: depth=0, C=US, O=xxxx, CN=xxxx.com
Tue Feb 26 17:29:33 2019 daemon.notice openvpn[21988]: Control Channel: TLSv1.2, cipher TLSv1/SSLv3 ECDHE-RSA-AES256-GCM-SHA384, 4096 bit RSA
Tue Feb 26 17:29:33 2019 daemon.notice openvpn[21988]: [xxxx.com] Peer Connection Initiated with [AF_INET]127.0.0.1:3443
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: SENT CONTROL [xxxx.com]: 'PUSH_REQUEST' (status=1)
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1,route 10.100.101.1,dhcp-option DNS 1.1.1.1,dhcp-option DNS 1.0.0.1,route-gateway 10.100.101.1,topology subnet,ping 10,ping-restart 120,ifconfig 10.100.101.4 255.255.255.0,peer-id 0,cipher AES-256-GCM'
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: OPTIONS IMPORT: timers and/or timeouts modified
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: OPTIONS IMPORT: --ifconfig/up options modified
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: OPTIONS IMPORT: route options modified
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: OPTIONS IMPORT: route-related options modified
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: OPTIONS IMPORT: --ip-win32 and/or --dhcp-option options modified
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: OPTIONS IMPORT: peer-id set
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: OPTIONS IMPORT: adjusting link_mtu to 1626
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: OPTIONS IMPORT: data channel crypto options modified
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: Data Channel: using negotiated cipher 'AES-256-GCM'
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: Data Channel Encrypt: Cipher 'AES-256-GCM' initialized with 256 bit key
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: Data Channel Decrypt: Cipher 'AES-256-GCM' initialized with 256 bit key
Tue Feb 26 17:29:34 2019 daemon.notice netifd: Interface 'VPN_client' is enabled
Tue Feb 26 17:29:34 2019 daemon.notice netifd: Network device 'tun0' link is up
Tue Feb 26 17:29:34 2019 daemon.notice netifd: Interface 'VPN_client' has link connectivity
Tue Feb 26 17:29:34 2019 daemon.notice netifd: Interface 'VPN_client' is setting up now
Tue Feb 26 17:29:34 2019 daemon.notice netifd: Interface 'VPN_client' is now up
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: TUN/TAP device tun0 opened
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: TUN/TAP TX queue length set to 100
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: /sbin/ip link set dev tun0 up mtu 1500
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: /sbin/ip addr add dev tun0 10.100.101.4/24 broadcast 10.100.101.255
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: /sbin/ip route add 127.0.0.1/32 via 10.1.16.1
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: /sbin/ip route add 0.0.0.0/1 via 10.100.101.1
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: /sbin/ip route add 128.0.0.0/1 via 10.100.101.1
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: /sbin/ip route add 10.100.101.1/32 via 10.100.101.1
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: GID set to nogroup
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: UID set to nobody
Tue Feb 26 17:29:34 2019 daemon.warn openvpn[21988]: WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this
Tue Feb 26 17:29:34 2019 daemon.notice openvpn[21988]: Initialization Sequence Completed
Tue Feb 26 17:29:35 2019 kern.info kernel: [ 5076.335297] eth1: link up (1000Mbps/Full duplex)
Tue Feb 26 17:29:35 2019 kern.info kernel: [ 5076.340124] br-lan: port 1(eth1) entered forwarding state
Tue Feb 26 17:29:35 2019 kern.info kernel: [ 5076.345804] br-lan: port 1(eth1) entered forwarding state
Tue Feb 26 17:29:35 2019 daemon.notice netifd: Network device 'eth1' link is up
Tue Feb 26 17:29:35 2019 daemon.info odhcpd[1590]: Using a RA lifetime of 0 seconds on br-lan
Tue Feb 26 17:29:35 2019 user.notice firewall: Reloading firewall due to ifup of VPN_client (tun0)
Tue Feb 26 17:29:37 2019 kern.info kernel: [ 5078.343418] br-lan: port 1(eth1) entered forwarding state
Tue Feb 26 17:29:38 2019 daemon.info dnsmasq-dhcp[2630]: DHCPREQUEST(br-lan) 192.168.8.232 f4:8e:38:f1:6a:d3
Tue Feb 26 17:29:38 2019 daemon.info dnsmasq-dhcp[2630]: DHCPACK(br-lan) 192.168.8.232 f4:8e:38:f1:6a:d3 XXXX
Tue Feb 26 17:30:00 2019 daemon.notice netifd: Network device 'tun0' link is down
Tue Feb 26 17:30:00 2019 daemon.notice netifd: Interface 'VPN_client' has link connectivity loss
Tue Feb 26 17:30:00 2019 daemon.notice netifd: Interface 'VPN_client' is now down
Tue Feb 26 17:30:00 2019 daemon.notice netifd: Interface 'VPN_client' is disabled
Tue Feb 26 17:30:01 2019 daemon.info odhcpd[1590]: Using a RA lifetime of 0 seconds on br-lan
Tue Feb 26 17:30:03 2019 kern.info kernel: [ 5104.334408] eth1: link down
Tue Feb 26 17:30:03 2019 kern.info kernel: [ 5104.337659] br-lan: port 1(eth1) entered disabled state
Tue Feb 26 17:30:03 2019 daemon.notice netifd: Network device 'eth1' link is down
Tue Feb 26 17:30:05 2019 kern.info kernel: [ 5106.334687] eth1: link up (1000Mbps/Full duplex)
Tue Feb 26 17:30:05 2019 kern.info kernel: [ 5106.339510] br-lan: port 1(eth1) entered forwarding state
Tue Feb 26 17:30:05 2019 kern.info kernel: [ 5106.345180] br-lan: port 1(eth1) entered forwarding state
Tue Feb 26 17:30:05 2019 daemon.notice netifd: Network device 'eth1' link is up
Tue Feb 26 17:30:05 2019 daemon.err stunnel: LOG3[17]: socket fd: Broken pipe (32)
Tue Feb 26 17:30:05 2019 daemon.notice stunnel: LOG5[17]: Connection closed: 28375 byte(s) sent to TLS, 4686 byte(s) sent to socket
Tue Feb 26 17:30:07 2019 kern.info kernel: [ 5108.342915] br-lan: port 1(eth1) entered forwarding state
Tue Feb 26 17:30:08 2019 daemon.info dnsmasq-dhcp[2630]: DHCPREQUEST(br-lan) 192.168.8.232 f4:8e:38:f1:6a:d3
Tue Feb 26 17:30:08 2019 daemon.info dnsmasq-dhcp[2630]: DHCPACK(br-lan) 192.168.8.232 f4:8e:38:f1:6a:d3 XXXX
Tue Feb 26 17:30:25 2019 daemon.notice netifd: Network device 'wlan-sta' link is down
Tue Feb 26 17:30:25 2019 daemon.notice netifd: Interface 'wwan' has link connectivity loss
Tue Feb 26 17:30:26 2019 daemon.notice netifd: wwan (29895): udhcpc: received SIGTERM
Tue Feb 26 17:30:26 2019 user.notice mwan3: ifdown interface wwan (unknown)
Tue Feb 26 17:30:26 2019 daemon.info odhcpd[1590]: Using a RA lifetime of 0 seconds on br-lan
Tue Feb 26 17:30:28 2019 kern.info kernel: [ 5129.484389] wlan-sta: authenticate with d0:72:dc:1e:4a:c3
Tue Feb 26 17:30:28 2019 kern.info kernel: [ 5129.503239] wlan-sta: send auth to d0:72:dc:1e:4a:c3 (try 1/3)
Tue Feb 26 17:30:28 2019 kern.info kernel: [ 5129.510736] wlan-sta: authenticated
Tue Feb 26 17:30:28 2019 kern.info kernel: [ 5129.542661] wlan-sta: associate with d0:72:dc:1e:4a:c3 (try 1/3)
Tue Feb 26 17:30:28 2019 kern.info kernel: [ 5129.552815] wlan-sta: RX AssocResp from d0:72:dc:1e:4a:c3 (capab=0x431 status=0 aid=3)
Tue Feb 26 17:30:28 2019 kern.info kernel: [ 5129.561368] wlan-sta: associated
Tue Feb 26 17:30:28 2019 daemon.notice netifd: Network device 'wlan-sta' link is up
Tue Feb 26 17:30:28 2019 daemon.notice netifd: Interface 'wwan' has link connectivity
Tue Feb 26 17:30:28 2019 daemon.notice netifd: Interface 'wwan' is setting up now