I've pushed some notes on v4 to github: https://github.com/FreeRADIUS/freeradius-server/blob/eb234d6bd979218367e463ea494e8e3bcc51803f/doc/antora/modules/ROOT/pages/index.adoc#why-v4 As for updates, we're still working on it. The only remaining feature to re-implement in v4 is RADIUS/TLS. Alan DeKok.