A relatively simple fix. I had tried rolling back my version of httpuv and R. However just copying the dll file from my laptops Win 10 httpuv library folder was sufficient to get things working.

As noted in the comments, installation was on a firewalled server. Maybe somewhere in the download of the files the dll wasn't formed correctly not sure. There was a handful of issue reports on the github for httpuv with the same problem. So not sure, but fortunately was just able to copy and paste and working copy over and it was resolved.