Also, the subject is somewhat misleading, so I've corrected it. It's probably not just 4.0 support. We've known that the ntirpc GSS implementation was buggy since at least late 2014 (when I joined the project), and probably since 2013 errors were introduced. We discussed some of these issues at Fall Bake-a-thon in 2014. It doesn't handle async calls well. It requires contiguous buffers, which requires much special casing both in the epoll receives and client callbacks. Back in March/April, I'd indicated that the next thing to work on was GSS for async zero copy. But Matt forbade it, and asked my boss to stop me from changing "his" code. While I'm around to help debug existing problems, since then I've not allocated time to write new code. Could somebody please look at that code before shipping V2.7?