Ian,
You are correct, the updates don't update the Kernel. If you remember, when Lee introduced UDP messaging in version update 20170619, this would initially only work with Kernels 4.4.xx or later, so 'Hotfix' update 20170706 was issued to allow UDP to work with earlier Kernels. I assume that the latest update includes the previous patches, so would fix that issue automatically, just not sure. Hopefully lee will respond and clarify the position.
Of course the error message may be something else entirely.
Best Regards
Peter