Hi,
There appears to be a bug with the UTM and IPv6 - these options do not function as they should.
I have to unstick everything in the firewall > ICMP settings in order to stop ICMP getting through the firewall.
I would have expected that with just "Allow ICMP through Gateway from external networks" then ICMP wouldn't get to the internal machines from an external source.
Bizarrely, with the "Gateway forwards trace route" ticked this also allows ICMP packets through to the internal machines.
Can this be raised as a bug please?