This is a new feature release in the INET 4.x branch. The central theme of this release is the maturation of the IPv6 protocol family, bringing it substantially closer to feature parity with IPv4. Highlights include a new declarative IPv6 network configurator, IPv6 multicast routing (MLD, and PIM-DM/PIM-SM over IPv6), node lifecycle support, Duplicate Address Detection, a modernized Mobile IPv6 (MIPv6) model with new Proxy Mobile IPv6 (PMIPv6) support, and IPv6 support in BGP (MP-BGP) and IPsec. Outside the IPv6 area, the release brings satellite and GNSS track mobility models with geographic visualization, a substantial overhaul of the STP and RSTP spanning tree models, major BGP improvements, TCP Path MTU Discovery, and a configurable RNG grouping mechanism. The release also contains numerous smaller improvements and bug fixes. Requires OMNeT++ 6.4 or later.