I have multiple Spectrum connections at different sites that I need to be able to monitor. For the past year that I have had these service installations, both IPv4 and IPv6 have functioned without any issue any allow me to send periodic ICMP and ICMPv6 traffic to monitor the cable modem's reachability.
Approx a month or so ago however, any ICMPv6 traffic inbound to my endpoints is being filtered. My devices have undergone no changes but have stopped responding to this traffic.
I can ping6 out from the endpoints, but they do not receive any inbound traffic of this type. I have powercycled as well as manually renewed the address leases with no change in behavior for the inbound traffic.
Why is this traffic being blocked? and can it please be re-allowed?