Software availability isn't really the problem. For most software there was no change at all ("connect to that host" or "listen to any device" and operating system will handle details), most software which needed adaption had it for a while (picking up a devices explicitly, handling of IPv6 addressees, ...) while maybe not equally good (missing GUI improvements for better handling of IPV6 addresses)

The problems, as I observe, are more in network infrastructure, routing, etc.