I've asked ISP for IPv6 range to check if it started to be more usable now than when I trtied it last time and it's still the same garbage as it was. There are still 2 ways how to get and address DHCPv6 and SLAAC and some things need one to work and other things the second, so you have to support both in your network. DHCPv6 is giving some machines /128 and some /64. Router for sometimes can't distinguish what's LAN and what's WAN. For example SSH can't be accessed from IPv6 at all and web correctly only from LAN, even when both are set to be LAN only. IPv6 was a mistake.