Problem:
On RouterOS up to at least v7.4.1 you can’t select ICMPv6 as IP protocol in the Tools -> Packet Sniffer
If you select icmp, you will not sniff any ICMPv6 traffic.
Solution:
The solution is to enter the ICMPv6 IP protocol ID – 58 – into the IP protocol field manually:
After that, ensure that you apply the settings. You can start sniffing ICMPv6 traffic immediately.