Where was the download logs that gave this error attempted from ?
It is possible you have DNS Rebinding protection blocking the url showing in the error mesage
You can try on that machine where the download attempt failed to do this in a command line window and see what you get
nslookup 192-168-178-54.C35706253CCB4DCA856A51903B66EB4C.plex.direct
I have responded to your forum topic Plex offline Download option never working - Plex Media Server / NAS & Devices - Plex Forum
