Just a note to myself as I spent many hours in finding out why my clients did not get an IPv6 address from my pfSense router/firewall:
If you are using a Netgear switch (I am using here a Netgear GS116E), you need to make sure that the option
"Block Unknown Multicast Address" is set to DISABLED.
If you have that option enabled the IPv6 router advertisement (RA) packets seem to be filtered out. For me this was not very obvious ...