As promised on #vyos here is an description about how to implement DHCPv6-PD on OpenBSD v6.3 amd64 with XS4ALL as ISP. I am willing to test changes done in VyOS to make this work. Also I am willing to answer questions about my setup. As this is a private project, testing and answering will be primarily done at weekends. I have at my home a FTTH connection from XS4ALL. The purpose of the here described process is to tell XS4ALL that my network is willing to process IPv6 packets so that IPv6 can enable a route to my IPv6 subnet in their routing table. XS4ALL tells me my IPv6 subnet and prefix at their website. This information is needed during this process. XS4ALL has given me an plain Modulater-Demodulater (MoDem) also called a media converter. This modem converts the fiber to ethernet and nothing more. Here is the process on OpenBSD v6.3 to setup an IPv4 and IPv6 enabled connection with XS4ALL.