Proton runs IPv6 6 through a nat and properly blocks incoming connections so that is not a problem here. Also while it isn’t the default on all routers it is still entirely possible for the router to have a firewall on IPv6 connections so no incoming connections can connect to your devices unless you have allowed it.





Any that refuse to comply with legal requirements won’t be around for long so it is hard to have a list of them or rely on them.