I haven't seen this, but the number of times my wan goes down is counted on one hand per year.
Regardless, I use a fairly simple bash script on my router that checks I can ping a reliable IP6 address every minute, and if it fails, I log to ntfy.
If it fails more than 3 times, I stop and restart wide-dhcpv6-client and log to ntfy, then wait 10 minutes before resuming per-minute checks. I do the same for the IP4 side.
(network_vars.sh includes network_vars_plus6.sh which is written as part of ppp's ip-up processing to log network info. You could pick any reliable ip6 host - I use google.dns IP6 address )
#!/bin/bash
#
# Script to monitor the stability of the plusnet IP6 connection
COUNT=0
TIMEOUT=3
PINGS=2
PINGWAIT=7
INTERTEST=60
POSTDOWNUP=600
function cleanup()
{
echo NOTICE: Exiting script
exit 0
}
trap cleanup SIGINT
NOW=$(date)
echo "[$NOW] NOTICE: monitor_plus6 $$ started"
echo
while true;
do
# These may change while we are monitoring so load them now
. ~/bin/network_vars.sh
TESTIP=$VALID_PUB_GW6_PLUS
# Try pinging gateway $PINGS times or for $PINGWAIT seconds
ping6 -c $PINGS -i 2 -w $PINGWAIT "$TESTIP" 2>&1 >/dev/null
if [ $? == 0 ];
then
if [ $COUNT -gt 0 ];
then
NOW=$(date)
echo "[$NOW] NOTICE: ping6 test successful after $COUNT failures"
echo ==============================================
fi
# If all ok then reset the counter and wait before retrying
COUNT=0
sleep $INTERTEST
continue
fi
# Increment the ping check count
let COUNT=$COUNT+1
NOW=$(date)
/usr/bin/curl -m 5 -u "ntfypublish:<censored>"
if [ $COUNT -lt $TIMEOUT ];
then
echo "[$NOW] WARNING: ping test to $TESTIP failed $COUNT times"
sleep $INTERTEST
continue
fi
# Ping has failed every $PINGWAIT for $COUNT times. Down and up the interface
/usr/bin/curl -m 5 -u "ntfypublish:<censored>"
echo ======================================================================
echo "[$NOW] ERROR: ping test to $TESTIP failed $COUNT times"
echo "[$NOW] ERROR: wide-dhcpv6 stop and start is next"
echo ======================================================================
trap - SIGINT
systemctl stop wide-dhcpv6-client.service
sleep 5
systemctl start wide-dhcpv6-client.service
trap cleanup SIGINT
NOW=$(date)
echo ======================================================================
echo "[$NOW] ERROR: stop - start completed. Waiting $POSTDOWNUP before testing again."
echo ======================================================================
# Wait before trying again afer downing and restoring the interface
sleep $POSTDOWNUP
done
