How to force watchdog to log reasons?

So I've installed and I'm running watchdog for some months now on BananaPi M1. I think it reboots the board when the default gateway has some issues. And that's fine, no problem with that. The board works 24/7 and it made 14+ days uptime without problems.

But things have changed and the board reboots at least few times a day (seems I have a problem with armbianmonitor -u - the board rebooted twice before it ended). And here's the problem. watchdog doesnt log anything or I'm unable to find any usefull info.

And watchdog.conf:

(it seems that the board went offline - maybe internet connection issues, but I have another one running that's also "logless" and they have almost the same config except for the gateway IP)

ping                    = 192.168.1.1
#ping                   = 172.26.1.255
interface               = eth0
#file                   = /var/log/messages
#change                 = 1407

# Uncomment to enable test. Setting one of these values to '0' disables it.
# These values will hopefully never reboot your machine during normal use
# (if your machine is really hung, the loadavg will go much higher than 25)
max-load-1              = 24
max-load-5              = 18
max-load-15             = 12

# Note that this is the number of pages!
# To get the real size, check how large the pagesize is on your machine.
#min-memory             = 1
#allocatable-memory     = 1

#repair-binary          = /usr/sbin/repair
#repair-timeout         = 60
#test-binary            =
#test-timeout           = 60

# The retry-timeout and repair limit are used to handle errors in a more robust
# manner. Errors must persist for longer than retry-timeout to action a repair
# or reboot, and if repair-maximum attempts are made without the test passing a
# reboot is initiated anyway.
#retry-timeout          = 60
#repair-maximum         = 1

watchdog-device = /dev/watchdog

# Defaults compiled into the binary
temperature-sensor      = /sys/class/thermal/thermal_zone0/temp
max-temperature = 80

# Defaults compiled into the binary
#admin                  = root
interval                = 10
logtick                = 60
log-dir         = /var/log/watchdog

# This greatly decreases the chance that watchdog won't be scheduled before
# your machine is really loaded
realtime                = yes
priority                = 1

# Check if rsyslogd is still running by enabling the following line
#pidfile                = /var/run/rsyslogd.pid