I've been reading about this lately and don't fully understand if I should make a rule for it or not. I don't have any internet facing devices and I don't need to manage anything remotely. I just run through the wizard (sg-1000) and uncheck allow IPv6 and reboot it and I'm done, everything works fine. After some reading on these forums and web searches should i allow icmp type 3 and 4/type any on wan for mtu discovery, do I need to do this as a home user? Also do you guys do this too?
Technically you should allow "ICMP type 3 code 4" (Destination Unreachable, Fragmentation needed but DF bit set) messages in on your WAN to be able to connect to sites that have reduced MTU for whatever reason. However that's not the only solution and for most of the connections the other solutions will solve the issue for you without having to the open holes in your firewall: