FWIW, I've been running my own synapse server for over two years. It's been IPv6-only since the beginning and I haven't had any problems. IPv4 servers that can

FWIW, I've been running my own synapse server for over two years. It's been IPv6-only since the beginning and I haven't had any problems. IPv4 servers that can't federate with me can go federate with some other dual-stack server that does.